Effect of N, N-Dimethylglycine on Homocysteine Metabolism in Rats Fed Folate-Sufficient and Folate-Deficient Diets

OBJECTIVE

This study aimed to investigate the effects of N,N-dimethylglycine (DMG) on the concentration and metabolism of plasma homocysteine (pHcy) in folate-sufficient and folate-deficient rats.

METHODS

In this study, 0.1% DMG was supplemented in 20% casein diets that were either folate-sufficient (20C) or folate-deficient (20CFD). Blood and liver of rats were subjected to assays of Hcy and its metabolites. Hcy and its related metabolite concentrations were determined using a liquid chromatographic system.

RESULTS

Folate deprivation significantly increased pHcy concentration in rats fed 20C diet (from 14.19 ± 0.39 μmol/L to 28.49 ± 0.50 μmol/L; P < 0.05). When supplemented with DMG, pHcy concentration was significantly decreased (12.23 ± 0.18 μmol/L) in rats fed 20C diet but significantly increased (31.56 ± 0.59 μmol/L) in rats fed 20CFD. The hepatic methionine synthase activity in the 20CFD group was significantly lower than that in the 20C group; enzyme activity was unaffected by DMG supplementation regardless of folate sufficiency. The activity of hepatic cystathionine β-synthase (CBS) in the 20CFD group was decreased but not in the 20C group; DMG supplementation enhanced hepatic CBS activity in both groups, in which the effect was significant in the 20C group but not in the other group.

CONCLUSION

DMG supplementation exhibited hypohomocysteinemic effects under folate-sufficient conditions. By contrast, the combination of folate deficiency and DMG supplementation has deleterious effect on pHcy concentration.

Functional assessment of hepatobiliary secretion by 11C-cholylsarcosine positron emission tomography

Positron emission tomography (PET) with ¹¹C-cholylsarcosine (¹¹C-CSar), a radiolabelled synthetic N-methylglycine (sarcosine) conjugate of cholic acid, is a novel molecular imaging technique that enables quantitative assessment of the individual transport steps involved in hepatic secretion of conjugated bile acids. Here, we present the method and discuss its potential clinical and scientific applications based on findings in the first human study of healthy subjects and patients with cholestasis. We also present a clinical example of a patient studied during and six months after an episode of drug-induced cholestatic liver injury.

Safety, tolerability and pharmacokinetics of open label sarcosine added on to anti-psychotic treatment in schizophrenia - preliminary study

BACKGROUND

Hypofunction of NMDA receptor-mediated neurotransmission might play a critical role in schizophrenia. Sarcosine, N- methylglycine and inhibitor of the glycine transporter-1 (Gly-T1), has been suggested as a novel treatment for schizophrenia.

METHODS

Open label sarcosine was added to 22 stabilized patients: 5 patients received 2 gm/d, and 17 received 4gm/d. Pharmacokinetics samples, clinical and cognitive parameters using PANSS, CGI and MCCB were collected for all patients.

RESULTS

Significant improvement was observed after one week of treatment on PANSS sub-scale of 'positive symptoms' (Z= -2.68; P=0.007) and 'general psychopathology' (Z= -3.02; P=0.003), an improvement in PANSS total score and CGI-S showed a trend (Z= -2.72; P=0.06; Z=-2.69; P=0.08). Speed of processing (MCCB subscale) improved significantly (Z=-2.13; P=0.03). Sarcosine exhibited linear kinetics, with a Tmax and t½ of ~1½- 2½ hr and ~1hr, respectively.

LIMITATIONS

This was a short period, open label pilot study with small sample size per dosage group.

CONCLUSIONS

Sarcosine is a safe compound and might be efficacious in the treatment of schizophrenia.

First-time-in-human study of GSK923295, a novel antimitotic inhibitor of centromere-associated protein E (CENP-E), in patients with refractory cancer

PURPOSE

GSK923295 is an inhibitor of CENP-E, a key cellular protein important in the alignment of chromosomes during mitosis. This was a Phase I, open-label, first-time-in-human, dose-escalation study, to determine the maximum-tolerated dose (MTD), safety, and pharmacokinetics of GSK923295.

PATIENTS AND METHODS

Adult patients with previously treated solid tumors were enrolled in successive cohorts at GSK923295 doses ranging from 10 to 250 mg/m(2). GSK923295 was administered by a 1-h intravenous infusion, once weekly for three consecutive weeks, with treatment cycles repeated every 4 weeks.

RESULTS

A total of 39 patients were enrolled. The MTD for GSK923295 was determined to be 190 mg/m(2). Observed dose-limiting toxicities (all grade 3) were as follows: fatigue (n = 2, 5%), increased AST (n = 1, 2.5%), hypokalemia (n = 1, 2.5%), and hypoxia (n = 1, 2.5%). Across all doses, fatigue was the most commonly reported drug-related adverse event (n = 13; 33%). Gastrointestinal toxicities of diarrhea (n = 12, 31%), nausea (n = 8, 21%), and vomiting (n = 7, 18%) were generally mild. Frequency of neutropenia was low (13%). There were two reports of neuropathy and no reports of mucositis or alopecia. GSK923295 exhibited dose-proportional pharmacokinetics from 10 to 250 mg/m(2) and did not accumulate upon weekly administration. The mean terminal elimination half-life of GSK923295 was 9-11 h. One patient with urothelial carcinoma experienced a durable partial response at the 250 mg/m(2) dose level.

CONCLUSIONS

The novel CENP-E inhibitor, GSK923295, had dose-proportional pharmacokinetics and a low number of grade 3 or 4 adverse events. The observed incidence of myelosuppression and neuropathy was low. Further investigations may provide a more complete understanding of the potential for GSK923295 as an antiproliferative agent.

Phencyclidine-induced cognitive deficits in mice are improved by subsequent subchronic administration of the glycine transporter-1 inhibitor NFPS and D-serine

Accumulating evidence suggests that the glycine modulatory site on the NMDA receptor could be potential therapeutic target for cognitive deficits in schizophrenia. The present study was undertaken to examine the effects of the glycine transporter-1 (GlyT-1) inhibitor, (R)-(N-[3-(4'-fluorophenyl)-3-(4'-phenylphenoxy)propyl])sarcosine (NFPS), on cognitive deficits in mice after repeated administration of the NMDA receptor antagonist phencyclidine (PCP). PCP (10 mg/kg/day for 10 days)-induced cognitive deficits were significantly improved by subsequent subchronic (2-week) administration of NFPS (1.0 and 3.0 mg/kg/day) or D-serine (600 mg/kg/day). However, PCP-induced cognitive deficits were not improved by a single administration of NFPS (3.0 mg/kg). Furthermore, Western blot analysis revealed that levels of GlyT-1 in the hippocampus, but not frontal cortex, of the PCP (10 mg/kg/day for 10 days)-treated mice were significantly higher than those of saline-treated mice. An in vivo microdialysis study revealed that repeated PCP administration significantly decreased the extracellular levels of glycine in the hippocampus, but not frontal cortex, of mice. These findings suggest that repeated PCP administration increased the density of GlyT-1 in the hippocampus of mouse brain, and that the GlyT-1 inhibitor NFPS could ameliorate cognitive deficits in mice after repeated administration of PCP.

Endogenous phospholipid metabolite containing topical product inhibits ultraviolet light-induced inflammation and DNA damage in human skin

BACKGROUND

N-palmitoylethanolamine (PEA) and organic osmolytes are endogenous components of the human epidermis and are generated from phospholipids in the stratum granulosum. PEA has been shown to exert potent antioxidant and anti-inflammatory activities. The endogenous organic osmolytes such as betaine and sarcosine control skin humidity, but have also been shown to inhibit ultraviolet (UV) light-induced oxidative stress in keratinocytes.

OBJECTIVES

To investigate the effect of a PEA- and organic osmolyte-containing topical product (Physiogel AI) on the development of UV light-induced erythema, thymine dimer formation and p53 tumor suppressor gene activation, as well as intercellular adhesion molecule 1 (ICAM-1) and Ki67 expression in normal human skin.

METHODS

The UV-induced erythema was measured by a spectrofluorometric method. Thymine dimers, p53, ICAM-1 and Ki67 were detected in skin biopsies using immunohistochemistry.

RESULTS

Physiogel AI cream significantly inhibited the development of UV light-induced erythema and thymine dimer formation in normal human skin, but did not alter the number of Ki67+ proliferating keratinocytes and the expression of p53 and ICAM-1.

CONCLUSIONS

Our results suggest that PEA and organic osmolytes might represent a new generation of compounds which suppress UV-induced photodamage.

Enteric-coated cholylsarcosine microgranules for the treatment of short bowel syndrome

Cholylsarcosine (CS) is a semisynthetic bile salt that may be useful in bile salt replacement therapy of short bowel syndrome (SBS). In SBS the bile salt pool becomes depleted, disturbing the uptake of dietary lipids and resulting in weight loss. Previous studies showed that CS in a simple capsule formulation of 1.5-12 g day(-1) can increase the uptake of lipids but often results in gastric irritation. In this work a microgranule dosage form was developed to protect the gastric mucosa while facilitating rapid generation of CS levels in the duodenum. CS microgranules were produced by wet granulation and coated with Eudragit L30D-55 in a fluidized-bed coater. The in-vitro dissolution rate of CS from the microgranules was investigated with USP apparatus under fasted- and fed-state conditions. CS release was delayed under simulated gastric conditions (pH 1.2 and 4.5) but was very fast at higher pH values (5.5, 5.8 and 6.5) more typical of the duodenum. In a pilot clinical trial, four patients received 4 g CS with meals (1.5 g with lunch, 2.5 g with dinner) for 1 week. The parameters investigated were fat absorption coefficient (FAC%), serum beta-carotene level and faecal weight. Although study numbers were too small to achieve statistical significance, the serum beta-carotene level and FAC% increased in the three patients who completed the trial. As expected, the fecal weight did not change. The results indicate that the CS microgranules are promising for the treatment of the intraluminal bile salt deficiency in patients with SBS.

Dimethylglycine supplementation does not affect plasma homocysteine concentrations in pre-dialysis chronic renal failure patients

OBJECTIVE

To determine whether daily dimethylglycine supplementation affects plasma homocysteine concentrations.

DESIGN AND METHODS

A randomized, blinded, crossover design was used. Seven pre-dialysis chronic renal failure patients consumed 400 mg of dimethylglycine or placebo daily for 28 days. Fasting blood samples and 12-h urine samples were collected at baseline and at the end of each treatment period for analysis.

RESULTS

No significant differences were observed in plasma homocysteine (P = 0.624), glycine betaine (P = 0.452) and methionine (P = 0.457) concentrations between dimethylglycine and placebo treatments.

CONCLUSION

Daily supplementation with dimethylglycine does not affect plasma homocysteine.

Glycine transporter I inhibitor, N-methylglycine (sarcosine), added to antipsychotics for the treatment of schizophrenia

BACKGROUND

Hypofunction of N-methyl-D-aspartate glutamate receptor had been implicated in the pathophysiology of schizophrenia. Treatment with D-serine or glycine, endogenous full agonists of the glycine site of N-methyl-D-aspartate receptor, or D-cycloserine, a partial agonist, improve the symptoms of schizophrenia. N-methylglycine (sarcosine) is an endogenous antagonist of glycine transporter-1, which potentiates glycine's action on N-methyl-D-aspartate glycine site and can have beneficial effects on schizophrenia.

METHODS

Thirty-eight schizophrenic patients were enrolled in a 6-week double-blind, placebo-controlled trial of sarcosine (2 g/d), which was added to their stable antipsychotic regimens. Twenty of them received risperidone. Measures of clinical efficacy and side effects were determined every other week.

RESULTS

Patient who received sarcosine treatment revealed significant improvements in their positive, negative, cognitive, and general psychiatric symptoms. Similar therapeutic effects were observed when only risperidone-treated patients were analyzed. Sarcosine was well-tolerated, and no significant side effect was noted.

CONCLUSIONS

Sarcosine treatment can benefit schizophrenic patients treated by antipsychotics including risperidone. The significant improvement with the sarcosine further supports the hypothesis of N-methyl-D-aspartate receptor hypofunction in schizophrenia. Glycine transporter-1 is a novel target for the pharmacotherapy to enhance N-methyl-D-aspartate function.

Oral bile acids reduce bacterial overgrowth, bacterial translocation, and endotoxemia in cirrhotic rats

Experiments were performed to test whether conjugated bile acid administration would decrease bacterial overgrowth, bacterial translocation, and endotoxemia in ascitic cirrhotic rats. Cholylsarcosine, a deconjugation-dehydroxylation resistant and cholylglycine, a deconjugation-dehydroxylation susceptible bile acid were used. Rats with CCl(4)-induced cirrhosis and ascites were fed cholylsarcosine, cholylglycine (both at 70 mg/kg/d), or placebo for 2 weeks. Healthy rats, as controls, were treated similarly. In cirrhotic rats receiving placebo, bile secretion from an acute biliary fistula was lower than in healthy rats (27.2 +/- 6.5 vs. 53.0 +/- 3.1 microL/kg/min; mean +/- SE, P<.05). The administration of conjugated bile acids to cirrhotic rats normalized bile secretion (cholylsarcosine, 51.8 +/- 6.29; cholylglycine, 52.72 +/- 8.9 microL/kg/min). Total ileal bacterial content was 6-fold higher in ascitic cirrhotic rats than in healthy rats. Conjugated bile acid administration reduced bacterial content to normal levels. Bacterial translocation was less in cirrhotic animals receiving conjugated bile acids (cholylsarcosine, 33%; cholylglycine, 26%) than in animals receiving placebo (66%). Endotoxemia was decreased in cirrhotic rats by conjugated bile acid feeding (cholylsarcosine, 0.098 +/- 0.002; cholylglycine 0.101 +/- 0.007 EU/mL) compared with placebo (0.282 +/- 0.124, P <.001). Survival was greater in animals receiving conjugated bile acids (cholylsarcosine, 10/15; cholylglycine, 11/15; placebo, 5/15). In conclusion, the administration of conjugated bile acids to ascitic cirrhotic rats increased bile acid secretion, eliminated intestinal bacterial overgrowth, decreased bacterial translocation, decreased endotoxemia, and increased survival. Oral conjugated bile acids may be useful in preventing bacterial translocation, endotoxemia, and spontaneous bacterial perotonitis in cirrhotic patients.

The effect of short-term dimethylglycine treatment on oxygen consumption in cytochrome oxidase deficiency: a double-blind randomized crossover clinical trial

OBJECTIVE

To study the effectiveness of dimethylglycine (DMG) on oxygen consumption (VO(2)) in children with Saguenay-Lac-Saint-Jean cytochrome-c oxidase (SLSJ-COX) deficiency (OMIM 220111).

STUDY DESIGN

In a crossover randomized double-blind clinical trial, 5 children with SLSJ-COX deficiency, who were stable and old enough to comply with VO(2) measurement, were treated with placebo or DMG for 3 days, and with the alternate treatment after a 2-week washout period. VO(2) was measured by indirect calorimetry before and after treatment. Dietary caloric intake was calculated for 3 days before each measurement. Mean caloric intakes per day were 1562 and 1342 kcal x m(-2) before and during placebo, 1,336 and 1,380 before and during DMG, respectively.

RESULTS

DMG was well tolerated and, in all cases, resulted in markedly increased blood DMG levels (617 + 203 mmol x L(-1)), versus 0 to 2 mmol x L(-1) without treatment. Mean VO(2) was lower after administration of either DMG (-1 +/- 3 mL x min(-1) x m(-2)) or placebo (-6 +/- 4), but neither difference was statistically significant. There was no detectable effect of DMG treatment on blood levels of lactate, pyruvate, bicarbonate, or pH. VO(2) values of patients (range, 101-135 mL x min(-1) x m(-2)) were lower than published norms (150-160 mL x min(-1) x m(-2)).

CONCLUSION

This study suggests that treatment with DMG does not substantially change VO(2) in children with SLSJ-COX deficiency.

Conjugated bile acid replacement therapy reduces urinary oxalate excretion in short bowel syndrome

BACKGROUND

Patients with short bowel syndrome (SBS) have steatorrhea, in part because of bile acid malabsorption that causes decreased bile acid secretion into the duodenum and consequent fat maldigestion. In SBS patients with colon in continuity, luminal calcium forms calcium fatty acid soaps rather than precipitating as insoluble calcium oxalate. Soluble oxalate is hyperabsorbed by the colon leading to hyperoxaluria and an increased risk for renal calcium oxalate stones and deposits. The authors hypothesized that oral ingestion of conjugated bile acids would increase fat absorption and thereby decrease calcium fatty acid soap formation and oxalate hyperabsorption.

METHODS

The effect of conjugated bile acid replacement therapy (9 g/d) on fecal fat excretion and urine oxalate excretion was measured in an appropriate patient, utilizing the metabolic balance technique. The effects of chronic bile acid replacement therapy on oxalate excretion and nutritional status also were measured in a 3-month outpatient study.

RESULTS

Natural conjugated bile acid replacement therapy reduced fecal fat excretion from 119 to 79 g/d (Delta40 g/d), and urinary oxalate excretion from 87 to 64 mg/d (966 to 710 micromol/d; Delta23 mg/d). Cholylsarcosine, a synthetic conjugated bile acid, had similar but less powerful effects. During a 3-month outpatient trial of natural conjugated bile acids (9 g/d), urine oxalate decreased to normal levels (27 mg/d) in association with weight gain, decreased hunger, and decreased hyperphagia.

CONCLUSION

Conjugated bile acid replacement therapy reduced fecal fat excretion, reduced urinary oxalate excretion, and improved nutritional status in a patient with SBS with colon in continuity, hyperoxaluria, and oxalate nephrolithiasis.

Dual effects of lisinopril on puromycin aminonucleoside nephrosis in unilaterally nephrectomized rats

The therapeutic effects of angiotensin converting enzyme inhibitor, lisinopril, on puromycin aminonucleoside (PAN)-induced nephrosis were investigated using unilaterally nephrectomized rats. Lisinopril showed potent dual effects on PAN nephrosis. Lisinopril treatment (50 mg/l in drinking water) from day 5 or day 9 reduced urinary protein excretion and suppressed the development of glomerular sclerosis at 8 weeks after PAN injection (150 mg/kg, i.p.), indicating a therapeutic effect on the nephrosis. Recovery of decreased anionic charge sites on the glomerular basement membrane was involved, at least in part, in the therapeutic action of lisinopril against proteinuria. On the other hand, oliguria and progressive azotemia derived from continuous deterioration of the renal function was induced if the treatment of lisinopril was started on the same day as PAN injection. The renal dysfunction induced by simultaneous administration of lisinopril with PAN could be abolished by combination dosing with sarcosine, an angiotensin II (AII)-receptor agonist. These results indicate that lisinopril treatment attenuates proteinuria by ameliorating the anionic charge barrier on the glomerular basement membrane and that it also protects against the development of chronic renal disease with segmental glomerular sclerosis, although AII depletion during the acute nephrotic stage exacerbates the renal damage in PAN nephrosis of unilaterally nephrectomized rats.

Effect of vitamin E on keratinocyte-modulation induced by lauroylsarcosine

The effect of vitamin E on the modulation of keratinocytes was studied in rats. A 1% lauroylsarcosine (LS) ointment caused skin erythema with keratinocyte-damage. A 30% vitamin E ointment markedly alleviated this erythema and protected keratinocytes from cell damage. Vitamin E (100 micrograms/ml) was also effective on LS (7.5 micrograms/ml)-induced proliferative reduction of cultured keratinocytes. On the other hand, ointment containing superoxide dismutase (SOD) (99,000 U/g) decreased the LS-induced erythema, suggesting that superoxide anion (O2-) produced from keratinocytes play an important role in the skin irritation. Indeed, LS induced O2- production from cultured keratinocytes. The O2- was significantly reduced by vitamin E and SOD, although vitamin E had no effects on O2- production in a xanthine-xanthine oxidase system, unlike the effect observed with SOD. These results indicate that vitamin E is an inhibitor of keratinocyte-modulation.

Cholylsarcosine, a new bile acid analogue: metabolism and effect on biliary secretion in humans

BACKGROUND

Cholylsarcosine, the synthetic conjugate of cholic acid and sarcosine, is resistant to deconjugation-dehydroxylation during enterohepatic cycling in rodents and improves lipid absorption in a canine model of intestinal bile acid deficiency caused by distal intestinal resection. Experiments were performed to define its metabolism and effect on biliary secretion in humans.

METHODS

The circulating bile acid pool was labeled with [14C]cholylsarcosine, and its turnover rate and biotransformation were determined by sampling bile daily. Cholylsarcosine (or cholyltaurine) was infused into the duodenum for 8 hours to define its effect on bile flow and biliary lipid secretion.

RESULTS

Cholylsarcosine was lost rapidly from the enterohepatic circulation with a t1/2 of 0.5 days. The compound was not biotransformed by hepatic or bacterial enzymes. Cholylsarcosine had choleretic activity similar to that of cholyltaurine but induced more phospholipid and cholesterol secretion than cholyltaurine in four or five subjects. Infusion of cholylsarcosine (or cholyltaurine) at a rate averaging 0.6 mumol.min-1.kg-1 gave a biliary recovery of 0.2 mumol.min-1.kg-1; this value is the Tmax for active ileal transport of conjugated bile acids in humans. Laboratory tests for liver injury remained within normal limits.

CONCLUSIONS

In humans, cholylsarcosine is not metabolized, is nontoxic, and has similar effects on biliary secretion as cholyltaurine. It appears safe to test in long-term studies the effect of cholylsarcosine on bile acid-deficiency states in humans.

Immunologic responses in healthy random-source cats fed N,N-dimethylglycine-supplemented diets

The immunomodulatory capacities of N,N-dimethylglycine (DMG) were examined in random-source cats. Blood mononuclear leukocytes of healthy adult cats that had negative results to tests for FeLV and feline immunodeficiency virus were exposed in vitro to various concentrations of DMG (10 to 1,000 micrograms/ml) and were evaluated for proliferative responses to T- or B-cell phytomitogens. Although increased, mean lymphocyte blastogenic responses to phytolectins in DMG-treated cultures did not differ significantly from responses of untreated cultures. For in vivo studies, cats were given a solution containing either 100 mg of DMG or a control solution without DMG orally at 8 AM and 6 PM for 40 consecutive days. On post-treatment day 24 and 25, mean blastogenic responses to phytolectins in DMG-treated and control cats inoculated 10 days earlier with an inactivated feline virus vaccine were similar. Cats given DMG and inoculated twice in a 3-week interval with a commercial vaccine containing inactivated feline herpesvirus-1 and feline calicivirus had significantly (P = 0.045) lower virus neutralizing serum antibody titers against feline herpesvirus-1, compared with titers of control cats, whereas feline calicivirus titers were similar in both groups. On day 25, mean serum interferon activity, induced after IV inoculation of Newcastle disease virus, was significantly (P = 0.021) lower in the DMG-treated cats. Results of this study of DMG in healthy cats failed to demonstrate enhancement of either specific or nonspecific immunity.

Sarcosine kinetics in pigs by infusion of [1-14C]sarcosine: use for refining estimates of glycine and threonine kinetics

To investigate in vivo the interconversion between glycine (Gly) and its N-methyl product sarcosine (Sar), [1-13C]Gly and [1-14C]Sar were infused into hourly fed pigs receiving diets with low- and high-threonine levels. An open two-pool model was developed to calculate Sar demethylation (DM) and Gly methylation (GM). During [1-14C]Sar infusion, intracellular Gly specific radioactivities (SA) in the liver and kidney were higher than plasma Gly SA, suggesting that demethylation of Sar occurred in those tissues. DM estimated by using hippuric acid (HA) as the production pool had a mean value of 1.55 mumol.kg-1.h-1, similar to the Sar production rate (mean 1.85 mumol.kg-1.h-1). GM was undetectable (less than 0.5 mumol.kg-1.h-1). These results suggest that, in fed pigs, Sar is produced mainly from choline catabolism and is degraded only to Gly in liver and kidney. On the assumption that Sar degradation gave rise only to Gly, the production rate of Gly (Gly PR) was calculated from [1-13C]Gly and [1-14C]Sar infusions using either the primary pools (plasma Gly and HA, respectively) or the secondary pools (HA and plasma Gly, respectively). The results were explained by a liver-plasma Gly exchange model. The whole body Gly irreversible loss, i.e., direct loss from plasma and liver, was calculated from this model to be 832 +/- 58 mumol.kg-1.h-1, showing that the estimation of Gly PR with [1-13C]Gly infusion and plasma Gly enrichment (599 +/- 56 mumol.kg-1.h-1) was a significant underestimate of the true value.(ABSTRACT TRUNCATED AT 250 WORDS)

New attachment in monkeys with experimental periodontitis with and without removal of the cementum

Experimental periodontitis was induced in monkeys by means of elastic orthodontic ligatures. The periodontally-involved teeth were then treated with different methods. At the end of the treatment period, the monkeys were sacrificed. The premolar-molar areas were dissected out and embedded in a low-viscosity embedding medium (Spurr). The results of the treatment procedures were analyzed on ground sections. Formation of new cementum and new bone was determined by means of tetracycline labeling. Root planing with an ultrasonic device or with hand instruments almost completely removed the cementum and a portion of the peripheral dentin. The root surface was more uneven after treatment with the ultrasonic device than after using hand instruments. No new attachment could be found after root planing. Cleaning of the periodontally-involved root surfaces with two detergents (cetylpyrimidinium chloride and sodium-N-lauroyl sarcosine) without root planing resulted in a significant amount of new attachment.

Suppression of murine IgE responses with amino acid polymer/allergen conjugates. V. By intranasal administration

Serum IgE antibody responses were generated in mice by intranasal exposure to grass pollen extract. Primary IgE responses were suppressed by the concomitant intranasal administration of a conjugate of polysarcosine and pollen extract which has been shown to be a potent tolerogen when given parenterally. Partial suppression of boosted IgE responses was observed when the conjugate was applied intranasally with a secondary challenge of unmodified extract. The data suggest that clinical schedules of intranasal application of tolerogenic conjugates can be devised to bring about specific IgE suppression.

Transmethylation of homocysteine to methionine: efficiency in the rat and chick

Experiments were conducted with young chicks and rats to quantify the efficacy of L-homocysteine as a methionine precursor. Linear growth responses were obtained to both L-methionine and L-homocysteine when added to a methionine-deficient intact-protein diet containing a plethora of cystine. Slope-ratio multiple regression methodology indicated L-homocysteine to be 64.5% as efficacious as L-methionine in rats and 62.5% as efficacious in chicks. Plasma-free methionine also increased linearly as graded levels of either L-methionine or L-homocysteine were added to the diet of rats. At higher dosages of L-homocysteine, betaine, but not choline, showed some efficacy in enhancing the conversion of homocysteine to methionine. In the linear response surface of the growth curve, however, supplemental betaine was without effect on L-homocysteine bioefficacy, as was also the case for supplemental sarcosine and N5-methyltetrahydrofolic acid.

Hypersarcosinemia with craniostenosis-syndactylism syndrome

Hypersarcosinemia with craniostenosis-syndactylism syndrome. After a sarcosine loading the sarcosine-glycine ratios seem to be a more reliable criterion to distinguish different genotypes than the sarcosine tolerance curves.

[Toxicology of epidithio-dioxopiperazines. 1. Studies on toxicity of cyclosarcosylsarcosineepitetrasulfide in guinea pigs and rats]

The present paper deals with the toxic effect of a mycotoxin of the group of epidithio-dioxopiperazines: cyclo-sarcosyl-sarcosin-epitetrasulfide, particularly upon the liver of guinea-pigs and rats. The sporidesmines, related to the compound tested, cause chronic obstructive cholangitis characteristic of a disease in sheep endemic in New Zealand. This type of cholangitis was attempted to be reproduced in order to establish an experimental model of producing biliary cirrhosis in animals. The acute and subacute LD50 in rats and guinea-pigs were determined intraperitoneally and intragastrally. In neither mode of application nor in short-term nor in chronic test could we find any specific, dose dependent changes of bile ducts. Merely, parenteral administration of lethal doses led to unspecific subcapsular liver necroses obviously due to direct diffusion of the toxic agent. The discrepancy between the efficacy of the toxic grass in New Zealand and the substance tested in the study is discussed.

The renin-angiotensin system and aldosterone secretion during sodium depletion in the rat

The role of the renin-angiotensin system in the control of aldosterone secretion was studied in the sodium-depleted rat. Administration of angiotensin II produced a significant increase in aldosterone secretion and arterial blood pressure in normal rats; simultaneous infusion of the angiotensin analogue. 1-sarcosine-8-alanine-angiotensin II, blocked both the pressor and the steroidogenic actions of angiotensin. Since the angiotensin II analogue was effective in blocking exogenous angiotensin II, an attempt was made to block endogenously formed angiotensin II in the sodium-depleted rat; infusions of large doses of the analogue produced a significant fall in arterial blood pressure, but aldosterone secretion failed to change. Bilateral nephrectomy also failed to decrease aldosterone secretion in the sodium-depleted rat even though arterial blood pressure fell. Since the secretion of corticosterone in these rats was high, it seemed likely that the failure of aldosterone secretion to fall resulted from an overriding influence of adrenocorticotropic hormone (ACTH). To test this hypothesis, the renin-angiotensin system was again blocked in sodium-depleted rats with three levels of anterior pituitary function. With high or intermediate rates of corticosterone secretion, a nonapeptide converting enzyme inhibitor (CEI) failed to influence aldosterone secretion. However, when the influence of ACTH was completely eliminated by hypophysectomy in sodium-depleted rats, the nonapeptide CEI produced a striking fall in aldosterone secretion. In contrast, arterial blood pressure was significantly reduced by CEI in rats with all three levels of anterior pituitary function. The data suggest a role for angiotensin II in the regulation of aldosterone secretion and the maintenance of arterial blood pressure in the sodium-depleted rat.

Hypertension of renal origin: evidence for two different mechanisms

Antibody to angiotensin 11, or a specific peptide competitive inhibitor of angiolensin II, was used to investigate the role of the renin-angiotensin system in two types of renal hypertension in rats. The data indicate that angiotensin II is in fact critically involved in the pathogenesis of the form of renal hypertension in which one renal artery is clamped and the contralateral kidney is left in place, but that it probably plays no significant role in the maintenance of experimental renal hypertension in which the opposite kidney has been removed.