The effect of induced reflections on human arterial waveforms

1. External compression of the human brachial artery results in waveform reflection. 2. Resonant waves are found superimposed on the original blood pressure signal. 3. The mechanism may be likened to the operation of an organ pipe with reflections at both ends of an arterial segment. 4. This has implications for measurements in arteries where external pressure is applied.

Effect of blood sampling on apomorphine-induced penile tumescence in erectile impotence: a case report

Apomorphine HCl (Apo) (0.5 mg sc), but not placebo, induced an erectile response (monitored with a mercury strain gauge) lasting 40 min in an impotent hyperprolactinemic patient. Serial blood sampling modified the 40 min erectile response. Prompt detumescence followed by complete or partial restoration of tumescence occurred each time blood was drawn. This observation points to the sensitivity of the Apo-erectile response to experimental procedures subjectively perceived as anxiogenic.

Production of fructose and fructose-3-phosphate in maturing rat lenses

PURPOSE

A large increase in glycation of crystallins between 1 and 8 months has been demonstrated in lenses obtained from aging rats. The objective of this study was to investigate if an age-associated increase in the levels of any of the phosphorylated and nonphosphorylated sugars in the aging rat lenses could be correlated with this increase.

METHODS

Lenses were obtained from Sprague-Dawley rats ranging in age from 2 to 20 months. Trichloroacetic extracts of these tissues were analyzed by using 31P-NMR for sugar phosphates and high-pressure liquid chromatography equipped with an electrochemical detector for sugars and polyols.

RESULTS

Although no elevation in the lenticular glucose levels was observed, an age-associated increase in the concentrations of polyol pathway-associated metabolites--sorbitol, fructose, sorbitol-3-phosphate, and fructose-3-phosphate--was detected. In contrast, no significant changes were observed in glycolytic or pentose shunt metabolites.

CONCLUSION

Aging lenses accumulate increased concentrations of fructose and fructose-3-phosphate. Because fructose-3-phosphate is a potent glycating agent and a potential in vivo source of 3-deoxyglucosone, its accumulation in the lens, along with fructose, may be a contributing factor in the age-associated increase of nonenzymatic glycation in rat lenses.

Metabolism of fructose-3-phosphate in the diabetic rat lens

Fructose-3-phosphate and sorbitol-3-phosphate are produced in diabetic rat lenses by a 3-phosphokinase. While sorbitol-3-phosphate appears to be an inert polyol phosphate, fructose-3-phosphate is a potent cross-linking agent and a potential in vivo source of 3-deoxyglucosone. The objective of this study was to investigate the production and decomposition of fructose-3-phosphate in the diabetic rat lens. The results indicate that this metabolite achieves a steady-state concentration of almost 1 mumol/g wet weight within 2 weeks after the onset of diabetes. These steady-state levels appear to be a consequence of a balance between its production from fructose and its further decomposition to 3-deoxyglucosone. This conclusion is supported by results from disappearance of fructose-3-phosphate in insulin-treated diabetic rats and in vitro incubations of fructose-3-phosphate with amines where production of 3-deoxyglucosone was detected using a number of different methods including mass spectrometry. In agreement with these results, elevated concentrations of 3-deoxyglucosone along with its detoxification product, 3-deoxyfructose, were detected in the diabetic rat lenses. Other sugars and sugar phosphates which were detectable in the diabetic rat lenses were glucose, fructose, glucose-6-phosphate, fructose-6-phosphate, and sedoheptulose-7-phosphate. In conclusion, results from this study suggest that fructose-3-phosphate and 3-deoxyglucosone are likely to be important contributors to the process of nonenzymatic glycation in diabetic rat lenses.

Baclofen is cytoprotective to cerebral ischemia in gerbils

The release of the neurotransmitter, glutamate, and the activation of receptor operated calcium channels, may increase the degree of damage in ischemic brain tissue. Inhibition of excitatory neurotransmitters should therefore result in cytoprotection of ischemic brain tissue. In this study we evaluated the effect of baclofen, an inhibitor of presynaptic glutamate release, on ischemic gerbil cortex, hippocampus (CA 1 and CA4), striatum and thalamus. Histological evaluation was done in a blind manner in 4 groups (total 36 animals): a control group (9 animals) and three groups (27 animals) with varying doses of baclofen. For cerebral ischemia, we used single episode of five minutes of arterial occlusion of the carotid arteries. Baclofen in doses of 0, 25, 50, and 100 mg/kg were given to different groups five minutes prior to ischemic insult. This was followed by intraperitoneal injections given 24 and 48 hours after the initial insult. Statistically significant histological cytoprotection was demonstrated. Doses of 25 mg/kg appeared to demonstrate significant protection of the cortex (p = 0.0002), the CA1 and CA4 regions of the hippocampus (p = 0.0004 and 0.0001) respectively. At a dose of 50 mg/kg, significant cytoprotection was demonstrated at the hippocampus (CA1 and CA4 regions), in particular at the CA4 region (p = 0.0029). The 100 mg/kg dose appeared to have most significant protection at the CA1 and CA4 regions of the hippocampus (both p = 0.0001), striatum (p = 0.0011), and the thalamus (p = 0.0008). All statistical comparisons were done using non-parametric tests (Mann-Whitney U test). Our study demonstrates that baclofen is cytoprotective to ischemic neuronal cells, especially in the hippocampus.(ABSTRACT TRUNCATED AT 250 WORDS)

Rifamycins: strain improvement program

Rifamycins are primarily produced by Gram-positive bacterium Amycolatopsis mediterranei, which belongs to the order Actinomycetales. These antibiotics, apart from their application against pathogens of tuberculosis and leprosy, have also been found to be effective against several other pathogens including Mycobacterium avium and Pneumococcus. Because of the importance of rifamycin, the producer strain A. mediterranei has been genetically manipulated since 1957 in order to develop a strain that can either produce larger amounts of rifamycin or derivatives of rifamycin. In this article, the importance of the producer strain, traditional methods (mutations and recombination) of strain improvement, their limitations, and the development of a cloning vector and transformation methods that have made recombinant DNA techniques accessible for genetic manipulations of A mediterranei are discussed.

Elevated dopa decarboxylase activity in living brain of patients with psychosis

The hypofrontality theory of the pathogenesis of schizophrenia predicts that cortical lesions cause psychosis. During a search for abnormalities of catecholaminergic neurotransmission in patients with complex partial seizures of the mesial temporal lobe, we discovered an increase of the rate of metabolism of an exogenous dopa tracer (6-[18F]fluoro-L-dopa) in the neostriatum of a subgroup of patients with a history of psychosis. When specifically assayed for this abnormality, patients with schizophrenia revealed the same significant increase of the rate of metabolism in the striatum. The finding is consistent with the theory that a state of psychosis arises when episodic dopamine excess is superimposed on a trait of basic dopamine deficiency in the striatum. The finding is explained by the hypothesis that cortical insufficiency, a proposed pathogenetic mechanism of both disorders, causes an up-regulation of the enzymes responsible for dopa turnover in the neostriatum as well as the receptors mediating dopaminergic neurotransmission.

Surveillance of acute diarrhoeal diseases at village level for effective home management of diarrhoea

One thousand thirtynine infants, 794 children in their second year of life and 445 children in their third year of life were followed up longitudinally from April 1984 to March 1985. Nearly 6 episodes of diarrhoea per annum, during infancy, 5.49 episodes in second and 4.19 episodes during third year of life respectively, were experienced. On an average, each episode of diarrhoea lasted for four days. 20% of infants, 6.43% of children between 1-2 years and 7.26% of children between 2-3 years, experienced weight loss of 300 gm. or more following episode of diarrhoea. Diarrhoea case fatality rate was 1.8% and 0.75% for infants and children between 1-3 years of age respectively. Home management of diarrhoeas by mothers with the advocacy of anganwadi workers and health workers yielded dividends. Sustained efforts of this kind may go a long way in management of diarrhoeas.

Effect of pH on the bioenergetics of perfused porcine lenses

Extracellular and intracellular pH has been shown to be an important physiological variable in many biological systems. However, studies on the effect of pH on the metabolic status of the mammalian lens have been few. It has been shown previously that a change in perfusate pH has a significant effect on the lens weight, ion transport, opacification and membrane potential. In this study we show that the bioenergetic status of the perfused pig lens, as assessed by 31P-NMR spectroscopy, is critically dependent on the pH of the bathing medium. At pH's of 7.6 and above, these perfused lenses maintained their nucleotide triphosphates concentrations steady for up to 4 days. In contrast, lenses perfused with identical media at pH 7.0, rapidly lost their nucleotide triphosphates. Our findings suggest that the pH of the extracellular pH may be an important parameter in maintaining the functional competence of the lens.

Recent trends in rifamycin research

Rifamycin is a clinically useful macrolide antibiotic produced by the gram positive bacterium Amycolatopsis mediterranei. This antibiotic is primarily used against Mycobacterium tuberculosis and Mycobacterium leprae, causative agents of tuberculosis and leprosy, respectively. In these bacteria, rifamycin treatment specifically inhibits the initiation of RNA synthesis by binding to beta-subunit of RNA polymerase. Apart from its activity against the bacteria, rifamycin has also been reported to inhibit reverse transcriptase (RT) of certain RNA viruses. Recently, rifamycin derivatives have been discovered that are effective against Mycobacterium avium, which is associated with the AIDS complex. Consequently, the importance of and demand for rifamycin has increased tremendously, the world over. In this article, recent trends in rifamycin research and accessibility of recombinant DNA techniques to increase rifamycin production are reviewed.

Localization of amplified MYC gene sequences to double minute chromosomes in acute myelogenous leukemia

Cytogenetic and molecular studies were performed on two dmin-bearing acute myelogenous leukemia (FAB-M2) samples. Both cases were characterized by complex karyotypes containing interstitial deletions of the long arm of chromosome 8 altering band 8q24.1, aberrations affecting the short arm of chromosome 17, and multiple double minute chromosomes (dmin). Using a 1.4 kb cDNA probe coding for the third exon of the MYC oncogene, DNA slot blots indicated MYC gene sequences were amplified in both samples. Fluorescence in situ hybridization using a 9.0 kb genomic probe for MYC was performed in one case and localized the amplified MYC gene sequences to the dmin. Neither patient achieved a complete remission using traditional induction chemotherapy. The complex karyology with amplification of MYC gene sequences appears to represent a poor prognostic subgroup of acute myelogenous leukemia.

Prolonged penile erections induced by hydroxyzine: possible mechanism of action

We describe a subject who developed prolonged penile erections on hydroxyzine. Molecular modelling showed that the hydroxyzine metabolite, norchlorcyclizine, has structural and conformational similarities to the trazodone metabolite, m-chlorophenylpiperazine. This suggests that a common pharmacological mechanism may underlie the ability of trazodone and hydroxyzine to induce erections.