Centrophenoxine: A true life extension drug?

 

Centrophenoxine: A true life extension drug? By James South MA

 

Centrophenoxine (CPH), also known as meclofenoxate, is one of the oldest nootropic drugs still in use - it was developed in 1959 at the French National Scientific Research Center (1). CPH is a compound (ester) of two biochemical's: dimethylaminoethanol (DMAE) and parachlorophenoxyacetic acid (PCPA) (see Fig. 1) (1). DMAE occurs naturally in some foods, especially fish, and is also a naturally occurring metabolite of choline in the human body. PCPA is a synthetic version of plant growth hormones called "auxins" (1). CPH is well absorbed orally, and after absorption a portion of the CPH is broken down in the liver to yield DMAE and PCPA. The DMAE is then converted to choline by the liver through adding a methyl group (CH3) to DMAE (2). Choline is simply trimethylaminoethanol (2), and is used to make such important biochemical's as acetylcholine and phosphatidyl choline. The remaining CPH then circulates through the bloodstream, accumulating especially in the heart and brain. "Pharmacokinetic studies of CPH revealed that ... much higher levels of DMAE were found in the brain after CPH treatment, as compared to DMAE alone, since apparently the esterified form of DMAE with PCPA penetrates much easier the blood-brain barrier." (2)

CPH: NOOTROPIC EXTRAORDINAIRE

CPH has been used successfully to treat a wide range of human diseases and psychoneurologic disorders. "Beneficial effects of CPH have been observed in various human disorders such as cerebral atrophy, brain injury, post apoplectic [post-stroke] status, chronic alcoholism, [and] barbiturate intoxication." (3) "Clinical trials with centrophenoxine in geriatric patients with such symptoms as confusion, psychosomatic asthenia [extreme weakness], and disturbances of memory and intellectual concentration revealed marked improvement after several weeks of treatment.... Clinical studies in European literature have reported a significant improvement of such symptoms as fatigue, irritability, confusional states, and loss of memory in the geriatric patients treated with centrophenoxine." (1) These human clinical trials demonstrate that CPH is an effective nootropic or "life enhancement drug". They do not show that CPH is a true-life extension drug - i.e. a drug that actually lengthens life. Yet there are tantalizing hints from the CPH experimental literature that do suggest CPH might also be a life extension drug.

CPH: EARLY LIFE EXTENSION STUDIES

In 1971, R. Hochschild published results of a study showing CPH lengthened lifespan in Drosophila Melanogaster - i.e. fruit flies (4). Hochschild notes that famed gerontologist Alex Comfort stressed "the usefulness of the adult fruit fly as an experimental model in gerontology." (4) Hochschild also noted that A.C. Tappel found evidence that fruit flies accumulated peroxidized phospholipids and lipofuscin similarly to senescent mammals (4). Hochschild fed seven different groups of fruit flies CPH, and 6 other biochemical's, comparing their eventual lifespan to a control group of flies. Although the tests showed interesting positive life extension effects of CPH, the results were probably understated. A key determinant of life span in fruit flies is the age of parents at mating - younger parents produce longer living offspring, older parents produce shorter living offspring (4). In the control group of male flies, parental age ranged from 9-54 days, while the CPH-treated flies all had parents 51 days old. In the control group of female flies, parental age ranged from 23-57 days, while the CPH-treated female flies had parents 51 days old. Thus there was a longevity bias in favor of the controls already, built into the experiment. In the male CPH group, there was only a non-significant 6% increase in mean life span over controls. However, the median life span (the age at which 50% of the flies were dead) of the CPH group was a significant 18% longer than the controls, while the maximum life span of the oldest CPH-treated fly was a significant 15% longer than the oldest control fly. The results among the female CPH-flies were much more impressive. Mean life span of the CPH group was 39% longer than controls, median life span was 28% longer than controls, and maximum life span was 23% longer than controls. Thus, at least for fruit flies, CPH is truly a life extension drug.

MICE LIVE LONGER WITH CPH

Hochschild next experimented with mice. He fed a group of 32 male Swiss Webster Albino mice CPH starting at age 8.6 months, comparing them to 31 control mice. CPH increased median survival time from start of the trial to 12.3 months, compared to 9.5 months for controls, a 29.5% increase. Mean survival time from start of trial was 9.73 months for controls, 12.39 months for the CPH mice, a 27.3% increase. The maximum survival time from start of trial was 17.4 months in the control group, 24.3 months in the CPH group, a 39.7% increase. Total maximum life span was 26.0 months, controls, and 32.9 months, CPH mice, a 26.5% increase.

Hochschild next used a compound broadly similar to CPH, Deaner ® (DMAE acetamidobenzoate), to treat aged mice (6). 57 A/J mice were fed Deaner ®, 57 were controls. Mice were 604-674 days old at start of trial, and the mean expected lifespan for this strain of mice is only 490 days (6), so these were definitely "geriatric mice." Median survival time from start of trial was 39 days for controls, 51 days for the Deaner ® mice, a 30.8% increase. Mean survival time from start of trial was 56.9 days for controls, 85.1 days for the Deaner ® mice, a 49.5% increase. The maximum survival time from start of trial was 273 days for the oldest control, 372 days for the oldest Deaner ® mouse, a 36.3% increase. The actual maximum life span was 912 days for the control, 1011 days for the oldest Deaner ® mouse, a 10.9% increase in total lifespan.

I. Zs.-Nagy tested the effects of BCE-001, an experimental drug variant of CPH that contains two dimethylamino groups in each molecule, compared to one such group in each CPH molecule (see Fig 2), on the lifespan of CFY rats (2). Female CFY rats were treated from 18 months of age with BCE-001. The untreated controls had a median life span of 23.6 months, typical for this strain, while the BCE-001 rats had a median life span of 29 months, a 23% increase. Since it is the dimethylamino group that gives CPH its metabolic power (more on this later), this experiment is an indirect indication of CPH's life extension potential.

The experiments just described provide some tentative reason to believe that CPH has the potential to extend life. Yet human CPH life extension trials have never been done, and may never happen. Is there enough understanding of the mechanism of action of CPH that might plausibly explain why it could be expected to extend life, even in humans?

Fortunately, there has been a great deal of biochemical and experimental research into CPH's mode of action that makes it reasonable to assume CPH is a life extension drug for humans.

THE MEMBRANE HYPOTHESIS OF AGING

To understand CPH's potential as a life extension drug, one must first understand the membrane hypothesis of aging (MHA), and the role of DMAE (the active ingredient of CPH) as a site-specific hydroxyl radical (OHR) scavenger. Chiefly elaborated by I. Zs.-Nagy (the most prolific CPH researcher), the MHA is a comprehensive theory of aging that might reasonably be viewed as a combination of the free radical theory of aging, the cross-linking theory of aging, and the essentiality of optimal cell membrane function for effective gene expression and optimal intracellular biochemistry. (Ed - Tapes of Professor Zs.-Nagy discussing his hypothesis of aging can be seen on www.antiaging-conference.com and purchased from IAS).

Zs.-Nagy points out that the main damaging factor for all biological components including proteins is the OHR, which is continuously produced in cells from the interaction of superoxide radicals (SOR) and hydrogen peroxide (H2O2) (8). Unfortunately, although these are cellular enzymatic defences against SOR and H2O2 (SOD and catalase/glutathione peroxidase), there are no enzymatic defences against OHR (9). However, cells that have an indirect defence mechanism against OHRs - i.e. continuous resynthesis. And this continuous resynthesis is dependent on gene expression, "...which consists of two main processes: (a) synthesis of various types of RNA (transcription) from the DNA as a template; and (b) synthesis of proteins (translation) using the various RNA products of process (a) by the ribosomes (8). (More on gene expression later.)

Zs.-Nagy also stresses that the cross-linking effect (and peroxidation of lipids) is a function of the physical density of the system wherein the OHR's occur (8). In a highly diluted system such as the cytosol (watery interior of the cell), OHR's might not generate intermolecular cross-links due to the relatively large distance to the next organic molecule. However, if the OHRs occur in a system of high density (such as the tightly molecularly packed membranes), the probability of intermolecular cross-links increases greatly. Thus it is the cell membrane that is most vulnerable to OHR attacks. According to Zs.-Nagy, "... it is known that some membrane proteins of hepatocytes display about ten-fold shorter half-life than do the average proteins in the cytoplasm...." (8), presumably due to greater OHR damage to membranes.

Although MHA applies to all cells to some extent, it is especially to the post-mitotic cells, which do not divide, that MHA is most strongly relevant. The main post-mitotic cells are brain, heart, and muscle cells. Zs.-Nagy remarks that high passive potassium and water permeability, and low passive sodium permeability, are key prerequisites for cell function, and over the lifetime of post-mitotic cells, due to ongoing chronic damage to the cell membrane, potassium and water permeability decreases (8). This causes a gradual accumulation of potassium inside cells, and a concomitant loss of water: "... there is a continuous relative dehydration of the living systems during their whole life span." (8) For example, Zs.-Nagy and colleagues found about 80% weight of intracellular water in the brain cells of one month old rats, decreasing to 72-73% by age 32 months, with the dry mass intracellular content increasing from 20 to 27-28%, a 40% relative increase (10).

THE MOLECULAR ENZYME KINETIC MODEL

This gradual thickening of the intracellular contents from thin, watery to more thickened, gelatin-like, has a profound effect on intracellular biochemistry and gene expression. The molecular enzyme kinetic model (MEKM), which has by now been experimentally well verified [see (8) and (11) for more detail], describes how intracellular environmental factors such as microviscosity (thinness or thickness of fluids) can significantly affect enzyme action and regulation. Damjanovich and associates found that the drop in brain cell water content from 80% to 72-74% previously mentioned was enough to reduce enzyme catalytic action up to 90% over the cell lifetime (11). Zs.-Nagy and Semsei found that in aging (26 month old) rats, total and messenger RNA synthesis in brain cortex cells dropped to only 40-50% of the RNA synthesis levels of young (1.5 month old) rats, which in turn necessarily reduces new protein synthesis to replace damaged cell membrane (and other) proteins (12).

When Zs.-Nagy and Semsei treated these old rats with CPH for 2 months, their brain and liver total and messenger RNA synthesis levels returned to the levels of the (1.5 month) young rats. This constitutes a literal complete regeneration of at least the first part of gene expression in the old, CPH-treated rats, making possible much more effective membrane repair (12).

THE VICIOUS CIRCLE OF AGING

The preceding brief exposition of the MHA, gene expression, and the MEKM barely scratches the surface of these topics. The interested reader is directed to references 8, 11 and 13 for more detail and references. Hopefully, however, the overview presented is sufficient to enable understanding of the "vicious circle" of aging at the cellular level.

  1. OHRs damage cell membranes continuously.
  2. Accumulating cell membrane damage gradually reduces potassium and water permeability, so water leaves and potassium accumulates, increasing intracellular viscosity.
  3. Increasing intracellular viscosity reduces enzyme action, including RNA synthesis (gene expression part 1).
  4. Reduced RNA synthesis reduces new protein synthesis (gene expression, part two).
  5. Reduced protein synthesis reduces efficiency of cell membrane damage repair, which damage is caused by 1), and the vicious circle of increasing cell membrane damage and cell dysfunction/aging rolls on.

SITE SPECIFIC ANTIOIDANTS

Since the "vicious circle of aging" starts with OHR damage to the cell membrane, it should be obvious that one solution would be to intersperse a OHR-scavenger throughout the cell membrane. The chief non-enzymatic OHR-scavenger is ascorbate (vitamin C) (9). Yet ascorbate is water-soluble, and membranes are composed of lipids, proteins, and glycoproteins (8). Ascorbate occurs in the watery compartments - blood, extra cellular fluid, cytoplasm, etc - not in the membrane. Tocopherol (vitamin E) is the chief membrane anti-oxidant, interspersed among the membrane lipids (14). Unfortunately, tocopherol does not quench OHR (9).

DMAE: SITE-SPECIFIC ANTIOXIDANT

DMAE is the active ingredient of CPH; the PCPA component is excreted in the urine (2). DMAE has been tested in a broad array of electron-spin resonance (ESR) - spin trapping experiments, including the use of PBN, 4-POBN, and DMPO (15). The OHR scavenger activity of DMAE has also "... recently been confirmed in a completely different system, applying a gamma radiation source for the generation of [OHRs] as well as the measurement of the carbonyl group formation on the BSA...." (2) Thus, the OHR-scavenging ability of DMAE is extremely well confirmed.

When CPH enters various cells, the CPH is hydrolyzed into DMAE and PCPA. The DMAE is then phosphorylated into phosphoryl-DMAE, which is then converted to phosphatidyl-DMAE (PhDMAE). PhDMAE is then incorporated into the cell membrane. Phosphatidyl-choline (PC) is a regular component of cell membranes, and PhDMAe is simply PC minus one methyl group, so it's a "natural" for incorporation into cell membranes. About 40% of PhDMAE persists in the membrane after 24 hours, in place of choline (2).

Is there experimental evidence that PhDMAE actually works in membranes as an effective site-specific antioxidant? Indeed there is. CPH was fed to 4, 16, and 28-month-old mice. Synaptic plasma membranes and liver microsomes were extracted and tested for fluidity. There was a significant increase in membrane fluidity of the CPH-fed mice compared to controls among all three age groups. The authors attributed the increase in membrane fluidity (which normally decreases with age) to the antioxidant effect of PhDMAE, noting, "such an effect could account for increased membrane fluidity in centrophenoxine-treated animals because it has been shown that membrane fluidity decreases as lipid peroxidation increases." (16)

Nagy and Zs.-Nagy compared the molecular weights of membrane proteins from 2, 12, and 24-month-old CFY rats. "The molecular weight distribution showed an age dependence: there was a clear shift toward the higher molecular weights in the adult and old rats. The observed alterations reflect an increased cross-linking of the proteins during aging due most probably to the OH free radical damage of the cell components. Centrophenoxine treatment for 2 months reversed this phenomenon in the old animals: the high molecular weight fractions decreased and the lower ones increased in the treated animals as compared to the old, untreated rats." (17)

Indirect evidence that CPH is acting primarily through the site-specific antioxidant action of DMAE comes from BCE-001, a "spin-off" of CPH. BCE-001 has two dimethylamino (CH3N) groups, while DMAE has only one. It is the nitrogen atom in the CH3N group that provides the OHR-quenching electrons (3). The reaction rate of BCE-001 in neutralizing OHRs is twice that of DMAE (2). DMAE can be, but BCE-001 cannot be, converted to choline or acetylcholine, life-enhancing biochemicals that might conceivably explain some of CPH's regenerative actions. BCE-001 seems only to act as a OHR scavenger (2). In experiments where BCE-001 is compared to CPH, BCE-001 achieves a similar or better result than CPH, at a lower dose or in a shorter time. For example, in the microviscosity improvement in the experiment discussed in the next section, BCE-001 achieved the result in 20 days that it took CPH 60 days to achieve (2). Since BCE-001 is believed to act through a OHR-quenching action, and is modelled on CPH (even including CPH's PCPA group), it seems likely therefore that CPH/DMAE is also acting through a site-specific OHR-quenching action. (Ed- BCE-001 remains at this time an experimental substance and therefore not currently commercially available, however, if it ever does become available, you can be sure that IAS will be the first organization to offer it).

Another indirect evidence of CPH/PhDMAE's role as a site-specific membrane antioxidant comes from a 1981 study by Bertoni-Freddari and co-workers (24). They found that CPH feeding significantly delayed the damaging effect of vitamin E deficiency on the brain cells of rats. Since vitamin E is the chief membrane antioxidant (14), this is clear evidence of CPH/PhDMAE's role as a membrane antioxidant.

CPH vs. MEMBRANE MICROVISCOSITY

The ability of CPH to improve membrane structure/function is also evidenced in a study by Nagy et al that measured changes in the synaptosomal membrane microviscosity in the brain cortex of rats during aging (18). The microviscosity, or fluidity, of synaptic membrane of young rats was 2.338; 2.370 for adult rats; and 2.632 for old rats. CPH treatment of old rats for 2 months reduced their membrane microviscosity level to 2.466, much closer to the adult than old control level. Given that "membrane fluidity decreases as lipid peroxidation increases," this experiment also suggests that CPH-derived PhDMAE is protecting membranes against lipid peroxidation. This in turn protects membrane proteins from cross-linking, since "proteins and amino acids are attacked [and cross-linked] by free radicals formed during lipid oxidation." (19) Nagy et al remark that "It has long been recognized that the dynamic properties of the lipid bilayer [membrane] are implicated in a series of membrane properties like ion and water permeability, enzyme activities, etc.... One can predict from this that the decreased fluidity of the synaptosomal membranes [during aging] ... should be accompanied by a series of functional impairments, e.g. the water and ion permeability of the membranes should be decreased...." (18)

CPH RESTORES WATER & ION PERMEABILITY

Does the CPH enhancement of cell membrane free radical protection and repair actually restore ion (potassium) and water membrane permeability? Indeed it does. Zs.-Nagy reported "... the effect of centrophenoxine on the intracellular ionic contents was studies using the X-ray microanalytic method.... The intracellular potassium content decreased about 10% in the dry mass of brain cortical cells of old, female Wilstan rats after a centrophenoxine treatment of three weeks." (20) Fulop and colleagues used a double-blind, placebo-controlled 8 week trial of CPH with 50 demented elderly adults (21). After just 8 weeks CPH treatment, the intracellular water content increased 3.38% in men, and 3.92% in women, with virtually no change in the placebo group. As Zs.-Nagy points out, "If the cytoplasm becomes rehydrated to only 2%, the potassium concentration of the cellular water will be about 20% lower than that of untreated old controls." (20) And to reiterate, increased intracellular water and decreased intracellular potassium reduces intracellular viscosity, or "thickness," of the cytoplasm. This in turn, according to the molecular enzyme kinetic model, improves the speed and efficiency of all intracellular enzyme processes, including the critical gene expression, which in turn allows for more effective membrane repair. Thus, CPH causes a "virtuous circle" of healing and repair, just the opposite of aging's "vicious circle."

CPH: LIFE EXTENSION DRUG

An absolutely definitive proof of CPH's status as a human life extension drug probably will not occur in the lifetime of those reading this article. Nevertheless, on the basis of the information presented in this article, it seems reasonable to provisionally accord CPH the status of "life extension drug" until and unless proven otherwise. CPH is considered an extremely non-toxic drug (21), in part because its chief metabolites - DMAE, PhDMAE, and choline - are natural constituents of food and the body. Doses used in human clinical trials are typically 600-2000 mg/day, given in divided dose at breakfast and lunch (21,22,23). As a life extension drug, 250 mg CPH twice daily may be adequate for life-long use. I. Zs.-Nagy has taken 500 mg CPH daily since 1976, and believes it has retarded his aging.

In a 1982 study on the effect of CPH on synaptic plasticity in old rats, Bertoni-Fredarri and associates compared two forms of CPH treatment (24). 27 month old rats were treated daily for 6 weeks (acute treatment), while 18 month old rats were treated 3 times weekly for 5 months (chronic treatment). The chronic treatment, started in rat "middle age," was able to prevent the decline in the numerical density of synapses that occurred in the controls from 18 to 23 months of age. The acute treatment was not able to prevent the even steeper decline that occurred from 23 to 28 months in the controls, although acute treatment did help several other parameters of synaptic regeneration. The lesson is simple: better to begin CPH in the 30s, 40, or 50s, than wait until the 70s or 80s.

Although CPH is generally safe and non-toxic, it can sometimes cause problems because it is such an effective cholinergic enhancer. Excessive brain/peripheral nervous system levels of acetylcholine (ACH) can lead to headaches, neck/jaw/shoulder muscle tension, insomnia, irritability, agitation and depression. This is not a toxicity reaction - it is simply too much of a good thing: ACH. If any of these symptoms occur, simply discontinue CPH for several days and then try a reduced dosage. Those especially sensitive to CPH may need to take it only on alternate days to avoid cholinergic excess. Any persons suffering from major depression, mania, seizure disorders or Parkinson's disease should avoid CPH, as too much ACH may worsen these conditions. Pregnant women should also avoid CPH.

WATER: THE ELIXIR OF LIFE

The reader should have discerned from the information presented on CPH and the MHA that gradual intracellular dehydration is a key feature, even cause, of aging. As Zs.-Nagy noted, "...there is a continuous relative dehydration of the living systems during their whole life spans." (8) This dehydration gradually slows down gene expression and intracellular enzyme activity, diminishing the ability of cells to repair themselves. An unstated assumption in both the human and animal experimental CPH work is that people (and animals) are always imbibing adequate water, i.e. that a chronic water intake deficiency is not occurring to contribute to the lifetime cellular dehydration. This is just the premise that Iranian expatriate physician F. Batmanghelidj challenges. In his two books, Your Body's Many Cries for Water (25) and Water for Health, for Healing, for Life (26), Dr. Batman, as his fans call him, argues that most people fail to drink adequate water, which he believes is 2 to 3 litres of water per day. Dr. Batman believes that one of the key fallacies of Western medicine is the belief that thirst is an adequate guide to water intake. He provides evidence that as we age, the thirst mechanism works ever more poorly, even when we are significantly dehydrated. He cites, for example, the classic study by Phillips and co-workers that compared the effects of 24 hours of water deprivation in seven healthy older men (65 - 75 years old) and seven healthy younger men (20 - 31 years old) (27). They concluded "that after 24 hours of water deprivation, there is a deficit in thirst and water intake in healthy elderly men, as compared with younger men...." (27)

Dr. Batman also points out that modern Westerners get much of their water intake from coffee, tea, soft drinks, beer and wine. Yet although these beverages contain water, they all have a diuretic effect, so that they cause a greater urinary loss of water than they contribute, and thus contribute to chronic (relative) dehydration.

In agreement with Zs.-Nagy, Dr. Batman also emphasizes the loss of intracellular water with aging. "Bruce and associates have shown that between the ages of twenty and seventy, the ratio of water inside the cells to the amount of water outside the cells drastically changes from 1.1 to 0.8." (28)

DROUGHT MANAGEMENT

Dr. Batman argues that a chronic long-term water deficiency will force the body to elaborate various hormones, including vasopressin, endorphins, prolactin, cortisone releasing factor, and rennin-angiotensin, to spread scarce water through various cells, tissues and organs on an emergency rationing basis (29). He also stresses the drought management role of histamine throughout his two books. Various tissues may get short-changed because of this, and have to function in a significantly dehydrated state. Batman believes this in turn gives rise to 6 conditions that are evidence the drought-management-programs are in effect: asthma, allergies, hypertension, constipation, type II diabetes, and autoimmune diseases (30). He believes a group of 10 conditions signals an even more drastic local dehydration emergency: heartburn, dyspeptic pain, anginal pain, lower back pain, rheumatoid joint pains, migraine headaches, colitis pain, fibromyalgic pains, bulimia, and pregnancy morning sickness (31).

Batman is also in agreement with Zs.-Nagy regarding the effect of intracellular dehydration on enzyme function. He cites the work of Ephrain Katchalski-Katzir of the Weizman Institute of Science, who has shown that; "proteins and enzymes of the body function more efficiently in solutions of lower viscosity." (32)

THE WATER CURE

Dr. Batman has a simple solution to the problem of chronic dehydration. He recommends that one drink 2-3 litres of water per day, from morning to night. He also recommends minimizing intake of coffee, tea, soft drinks, beer and alcohol. He advises drinking this water, through choice and force of will, whether or not there exists a sensation of thirst. Batman believes that the sensation of thirst atrophies in a person chronically water deficient, and so is not a reliable guide to water intake. I have interviewed various people following Dr. Batman's program, some as young as there 30's. Many have remarked that initially they did not have thirst to support drinking 2-3 litres of water per day, and found it rather burdensome. However, with continued long-term increased water intake, their thirst sensations intensified, and they began to thirst for their 2-3 litres per day.

CPH + H2O: A SIMPLE LONGEVITY PROGRAM

The human body is about 70% water, although among the dehydrated elderly this may be an overly high figure. It should not be surprising therefore that a gradual lifelong intracellular dehydration would impair the biochemistry of life, which occurs in the watery medium of the cells. John Watterson, in a classic 1988 review on "The role of water in cell architecture" (33), provides evidence that water clusters even help make up the sub cellular architecture of the cell, that water is not just a background medium in which biochemical reactions occur. Given the discussion in this article revealing CPH's ability to repair cell membranes in a manner that makes it easier to rehydrate the intracellular mass, and given that the only way to get large quantities of water on a regular basis is to drink it, it should not be surprising that the program of taking 500 mg - 2000 mg CPH daily, plus drinking 2-3 litres of water daily, may turn out to be a simple yet elegant and effective life extension combination.

REFERENCES

1. Nandy, K. (1978) "Centrophenoxine: effects on aging mammalian brain" J Am Ger Soc 26, 74-81.
2. Z.s-Nagy, I. (1994) "A survey of the available data on a new nootropic drug, BCE-001" Ann NY Acad Sci 717, 102-14.
3. Zs.-Nagy, I. & Semsei, I. (1984) "Centrophenoxine increases the rates of total and mRNA synthesis in the brain cortex of old rats: an explanation of its action in terms of the membrane hypothesis of aging" Exp Geront 19, 171-78.
4. Hochschild, R. (1971) "Effect of membrane stabilizing drugs on mortality in drosophila melanogaster" Exp Geront 6, 133-51.
5. Hochschild, R. (1973) "Effect of dimethylaminoethyl p-chlorophenoxyacetate on the life span of male Swiss Webster albino mice" Exp geront 8, 177-83.
6. Hochschild, R. (1973) "Effect of dimethylaminoethanol on the life span of senile male A/J mice" Exp Geront 8, 185-91.
8. Zs.-Nagy, I. (1989) "On the role of intracellular physicochemistry in quantitative gene expression during aging and the effect of centrophenoxine. A review." Arch Geront Geriatr 9, 215-29.
9. Levine, S. & Kidd, P. Antioxidant Adaption. S.F.: Biocurrents Div., ARG. 1986. P.48.
10. Zs.-Nagy, I. et al (1981) "Alterations in total content and solubility characteristics of proteins in rat brain and liver during aging and centrophenoxine treatment" Exp Geront 16, 229-40.
11. Damjanovich, S. et al (1989) "Application of a molecular enzyme kinetic model for aging cells and tissues" Arch Geront Geriatr *, 37-45.
13. Zs.-Nagy, I. (2003) "The membrane hypothesis of aging" IAS Anti-Aging Bulletin 4 (16), 21-31.
14. Levine & Kidd, pp. 55-7.
15. Zs.-Nagy, I. & Floyd, R. (1984) "Electron spin resonance spectroscopic demonstration of the hydroxyl free radical scavenger properties of dimethylaminoethanol in spin trapping experiments confirming the molecular basis for the biological effects of centrophenoxine." Arch Geront Geriatr 3, 297-310.
16. Wood, W. et al (1986) "Fluidizing effects of centrophenoxine in vitro on brain and liver membranes from different age groups of mice" Life Sci 39, 2089-95.
17. Nagy, K. & Zs.-Nagy, I. (1984) "Alterations in the molecular weight distribution of proteins in rat brain synatosomes during aging and centrophenoxine treatment of old rats" Mech Ageing Dev 28, 171-6.
18. Nagy, K. et al (1983) "Alterations of the synaptosomal membrane 'microviscosity' in the brain cortex of rats during aging and centrophenoxine treatment" Arch Geront Geriatr 2, 23-39.
19. Zs.-Nagy, I. & Nagy, K. (1980) "On the role of cross-linking of cellular proteins in aging" Mech Ageing Dev 14, 245-51.
20. Zs.-Nagy, I. (1978) " A membrane hypothesis of aging" J Theor Biol 75, 189-95.
21. Fulop, T. et al (1990) "Effects of centrophenoxine on body composition and some biochemical parameters of demented elderly people as revealed in a double-blind clinical trial" Arch Geront Geriatr 10, 239-51.
22. Izumi, K. et al (1986) "Meclofenoxate therapy in tardive dyskinesia: a preliminary report" Biol Psychiatr 21, 151-60.
23. Marcer, D. & Hopkins, S. (1977) " The differential effects of meclofenoxate on memory loss in the elderly" Age Ageing 6, 123-31.
24. Bertoni-Freddari, C. et al (1982) "In vivo effects of vitamin E-deficiency on the intracellular monovalent electrolyte concentrations in brain and liver of rat" Mech Ageing Dev 16, 169-80.
25. Batmanghelidj, F. Your Body's Many Cries for Water, Falls Church, VA: Global Health Solutions, 1995. 2nd Ed.
26. Batmanghelidj, F. Water for Health, for Healing. For Life. NY: Warner Books, 2003.
27. Phillips, P. et al (1984) "Reduced thirst after water deprivation in healthy elderly men" NE J Med 311, 753-9.
28. Batmanghelidj, 2003, p.27.
29. Batmanghelidj, 2003, pp. 193-99.
30. Batmanghelidj, 2003, p.59.
31. Batmanghelidj, 2003, pp.59-60.
32. Katchalski-Katzir, E. (1984) "Conformational Changes in biological macromolecules" Biorheology 21, 57-74.
33. Watterson, J. (1988) "The role of water in cell architecture" MOI Cell Biochem 79, 101-5.