Nodal-paranodal antibodies in HIV-immune mediated radiculo-neuropathies: Clinical phenotypes and relevance.

BACKGROUND: The frequency of nodal-paranodal antibodies in HIV-infected patients with chronic immune-mediated radiculo-neuropathies (IMRN) has not been previously described. METHODS: HIV-infected patients who met the inclusion criteria for chronic IMRN were screened for immunoglobulin G (IgG) antibodies directed against nodal (neurofascin (NF)186) and paranodal (NF155, contactin-1 (CNTN1) and contactin-associated protein(Caspr1)) cell adhesion molecules, using a live, cell-based assay. To explore potential pathogenicity, binding of human IgG to myelinated co-cultures was assessed by incubation with patients' sera positive for nodal or paranodal antibodies. Normal human serum was added as a source of complement to assess for complement activation as a mechanism for myelin injury. RESULTS: Twenty-four HIV-infected patients with IMRN were included in the study, 15 with chronic inflammatory demyelinating polyneuropathy (CIDP), 4 with ventral root radiculopathies (VRR), and 5 with dorsal root ganglionopathies (DRG). Five patients with CIDP had combined central and peripheral demyelination (CCPD). Three patients (12.7%) tested positive for neurofascin IgG1 antibodies in the following categories: 1 patient with VRR was NF186 positive, and 2 patients were NF155 positive with DRG and mixed sensory-motor demyelinating neuropathy with optic neuritis, respectively. CONCLUSION: The frequency of nodal-paranodal antibodies is similar among IMRN regardless of HIV status. Interpretation of the results in the context of HIV is challenging as there is uncertainty regarding pathogenicity of the antibodies, especially at low titres. Larger prospective immune studies are required to delineate pathogenicity in the context of HIV, and to establish a panel of antibodies to predict for a particular clinical phenotype.

Enhancing soil health and fruit yield through Tephrosia biomass mulching in rainfed guava (Psidium guajava L.) orchards.

Leguminous crop Tephrosia candida has high biomass production and contains a substantial quantity of nutrients within its biomass. Starting in 2019, a long-term study was done to find the best Tephrosia candida dose for mulching in guava orchards. The study had four treatments: T1 = 3.0 kg dry biomass m-2 of the plant basin, T2 = 2.0 kg, T3 = 1.0 kg, and T4 = control (no mulch). Every year, the treatments imposed in the month of August. The third year (2021-2022) results indicated that mulching with 3 kg of biomass m-2 increased trunk diameter, fruit yield, fruit weight, specific leaf area, total leaf chlorophyll, and leaf macro- and micro-nutrients. At 3.0 kg m-2, mulching improved soil properties such as EC, available nitrogen, available phosphorus, exchangeable potassium, DTPA extractable micronutrients (Fe, Zn, Cu, and Mn), total organic carbon (Ctoc), soil organic carbon (Csoc), organic carbon fractions, and microbial biomass carbon between 0-0.15 m and 0.15-0.30 m. There was an increasing trend in dehydrogenase activity (DHA) and fluorescein diacetate (FDA). The Tephrosia leaf litter exhibited decay constants of 1.27 year-1, and the carbon content was 40.11%. Therefore, applying Tephrosia biomass mulching at a rate of 3.0 kg m-2 is a viable long-term solution for enhancing soil fertility and sequestering carbon.

Improvement of rooting and growth in kiwifruit (Actinidia deliciosa) cuttings with organic biostimulants.

Seaweed extracts have shown profoundly positive effects on crop growth, quality and reproduction in diverse agricultural and horticultural crops. Seaweed extracts can be used to promote the rooting and growth of cuttings in perennial fruit species like kiwifruit (Actinidia deliciosa). In this study, the cuttings were treated with 1, 5, 10 and 50% solutions of G Sap (Gracilaria edulis), K Sap (Kappaphycus alvarezii), AN (Ascophyllum nodosum), EM (Ecklonia maxima), HA (Humic acid) and control (water) for 6 h as base dipping. Subsequently, the treatments of G Sap, K Sap, AN, EM, HA and control were repeated every 15 days for a period of six months as application of 50 ml solutions in the potted cuttings. All the treatments exhibited significant effects on the rooting percent in all the kiwifruit cultivars, namely 'Monty', 'Abott', 'Hayward', 'Allison' and 'Bruno' (P ≤ 0.01) as compared to the control. Shoot and root growth parameters including leaf number per cutting, number of roots per cutting, number of branches, plant height, shoot diameter, root length, root diameter and root weight were all positively increased with the application of seaweed extracts (P ≤ 0.05). Cuttings treated with seaweed extract exhibited significantly higher levels of pigments (chlorophyll a, chlorophyll b and total carotenoids), metabolites (total carbohydrates and soluble phenols) and less electrolyte leakage as compared to the control cuttings. Significant positive and negative correlations were observed between biochemical parameters combined with plant nutrient concentration. Principal component analysis (PCA) revealed that PC1 and PC2 (first two principal components) accounted for 75% of the entire variation. While, PC1 accounted for 63% of the total variation, PC2 accounted for 11% of the total variation. The leaves and the roots of kiwifruit cultivar 'Hayward' treated with G Sap at 10%, K Sap at 10%, AN at 10%, EM at 10%, HA at 10% exhibited higher expression of all four root promoting candidate genes (GH3-3, LBD16, LBD29 and LRP1) compared to the control. Therefore, it can be concluded that, seaweed extract and humic acid can be used as a suitable alternative to synthetic hormones for promoting the rooting and growth of kiwifruit cuttings.

Unraveling the pathways influencing the berry color and firmness of grapevine cv. Flame Seedless treated with bioregulators using biochemical and RNA-Seq analysis under semi-arid subtropics.

Plant bioregulators (PBRs) regulate developmental and physiological processes in plants. In this study, biochemical and transcriptomic analyses were conducted to evaluate the influence of PBRs [abscisic acid (ABA), benzothiadiazole (BTH), ethephon, and prohexadione-calcium (Pro-Ca)] on the grapevine cv. Flame Seedless under semi-arid subtropics. This study aims to see the effect of exogenous application of PBRs on overall berry quality, including uniformity of berry color. Uniform colored berries, the maximum total soluble solids (TSS) and total antioxidant activity (TAoA), and the highest total phenolics (TPC) and flavonoids (TFC) contents were obtained with the treatments, namely, 400 mg L-1 ethephon and 400 mg L-1 ABA. Further, RNA-Seq analysis has also identified some key DEGs like UFGT (VIT_16s0039g02230), GST (VIT_04s0079g00690), and chalcone synthase (CHS) (VIT_05s0136g00260) which were part of the anthocyanin biosynthesis pathway controlling grape berries color. Thus, ethephon (400 mg L-1) and ABA (400 mg L-1) were found promising for attaining greater uniformity in berry color development because of increased total anthocyanins content. In addition, they were also found associated with enhanced TAoA, TPC, and TFC. Hence, ethephon and ABA can be recommended for improving the berry quality.

Quality evaluation of co-composted wheat straw, poultry droppings and oil seed cakes.

Poultry droppings, neem cake, castor cake, jatropha cake and grass clippings were used separately as organic nitrogen additives to decrease the high C:N ratio of wheat straw. Composting was carried out aerobically in presence of fungal consortium developed by including Aspergillus awamori, Aspergillus nidulans, Trichoderma viride and Phanerochaete chrysosporium. The degraded product was characterized to assess the technical viability of organic nitrogen supplements as well as fungal consortium in improving the quality of compost and hastening the process of decomposition of high lignocellulolytic waste. Evaluation of maturity showed that mixture of wheat straw, poultry dropping and jatropha cake had the lowest C:N ratio of 10:1, the highest humic acid fraction of 3.15%, the lowest dehydrogenase activity and a germination index exceeding 80% in 60 days of decomposition. Inoculated and grass clipping amended wheat straw-poultry dropping mixture resulted in compost with highest humus content of 11.8% and C:N ratio of 13.5, humic acid fraction of 2.84% and germination index of 59.66%. Fungal consortium was effective in improving the humus content of all the composted mixtures. In some treatments, germination index could not be correlated with C:N ratio. Non edible oil seed cake supplemented substrate mixtures did not respond to fungal inoculation as far as C:N ratio was concerned.

Autogenous regulation of the positive regulatory qa-1F gene in Neurospora crassa.

In Neurospora crassa, the qa-1F regulatory gene positively controls transcription of all genes in the quinic acid (qa) gene cluster. qa-1F is transcribed at a low, uninduced level but is subject to strong (50-fold), autogenous regulation as well as to control by the negative regulatory gene, qa-1S, and the inducer quinic acid. Cloned qa-1F DNA sequences hybridize to two related mRNAs of 2.9 and 3.0 kilobases. When wild-type (qa-1F+) cultures are transferred to inducing conditions, qa-1F mRNA increases for 4 h, remains somewhat level, and decreases after 8 to 10 h. That this control is autogenous, i.e., that the qa-1F gene controls the synthesis of its own mRNA, is indicated by the presence of approximately the same low level of qa-1F mRNA in poly(A)+ RNA from noninducible qa-1F- mutant cultures under inducing conditions as that observed in uninduced wild-type cultures. The qa-1S gene also regulates the transcription of qa-1F, since a qa-1S- mutant, whether in noninducing or inducing conditions, contains a level of qa-1F mRNA that corresponds to the low level observed in uninduced wild-type cultures. These results corroborate the hypothesis (M. E. Case and N. H. Giles, Proc. Natl. Acad. Sci. USA 72:553-557, 1975; V. B. Patel, M. Schweizer, C. C. Dykstra, S. R. Kushner, and N. H. Giles, Proc. Natl. Acad. Sci. USA 78:5783-5787, 1981; L. Huiet, Proc. Natl. Acad. Sci. USA 81:1174-1178, 1984) that the qa-1F gene encodes an activator protein and acts positively in controlling transcription of itself and the other qa genes.

Genetic regulation of the qa gene cluster of Neurospora crassa: induction of qa messenger ribonucleic acid and dependency on qa-1 function.

An in vitro protein-synthesizing system (rabbit reticulocyte) was programmed with total polyadenylated messenger ribonucleic acid from wild type and various mutants in the qa gene cluster of Neurospora crassa. The products of two of the qa genes, quinate dehydrogenase (qa-3+) and dehydroshikimate dehydratase (qa-4+), were identified by specific immunoprecipitation and sodium dodecyl sulfate-slab gel electrophoresis. The results indicated that for both genes induction of a specific enzyme activity by quinic acid depends on the de novo synthesis of a specific polypeptide and on the de novo appearance of specific messenger ribonucleic acid detectable by the in vitro translation assay. Furthermore, the results indicated that the appearance of this messenger ribonucleic acid is under the control of the qa-1 gene. The simplest interpretation of these results appears to be that induction of enzyme activity in the qa system is mediated by events at the transcriptional level.

Purification of the arom multienzyme aggregate from Euglena gracilis.

The arom multienzyme complex that catalyzes steps two through six in the prechorismate polyaromatic amino acid biosynthetic pathway has been purified up to 2000-fold from Euglena gracilis. The native arom aggregate has a molecular weight of approx. 249 000 based on a sedimentation coefficient of 9.5 and Stokes radius of 60 angstrom. A comparison between the arom aggregates of Neurospora crassa and Euglena gracilis and the possible phylogenetic relationships between the organisms are discussed.

DNA sequence, organization and regulation of the qa gene cluster of Neurospora crassa.

In Neurospora, five structural and two regulatory genes mediate the initial events in quinate/shikimate metabolism as a carbon source. These genes are clustered in an 18 x 10(3) base-pair region as a contiguous array. The qa genes are induced by quinic acid and are coordinately controlled at the transcriptional level by the positive and negative regulators, qa-1F and qa-1S, respectively. The DNA sequence of the entire qa gene cluster has been determined and transcripts for each gene have been mapped. The qa genes are transcribed in divergent pairs and two types of transcripts are associated with each gene: basal level transcripts that initiate mainly from upstream regions and are independent of qa regulatory gene control, and inducible transcripts that initiate downstream from basal transcripts and are dependent on qa-1F binding to a 16 base-pair sequence. We discuss how both types of transcription relate to the organization of the qa genes as a cluster and how this may impose constraints on gene dispersal.

Alcohol and the heart: biochemical alterations.

A considerable amount of attention has focused on the cardiovascular events associated with ethanol consumption. The available evidence suggests that moderate ethanol consumption is associated with reduced risk of coronary heart disease, i.e., vessel events. In contrast, this review is primarily concerned with ethanol and heart muscle damage. Clinical features of the consequences of prolonged and excessive ethanol consumption encompass defects in myocardial contractility and derangement of cellular architecture, including disarray of the contractile elements. Although the incidence of heart muscle abnormalities in alcohol misusers is generally higher than previously considered, the mechanisms are only just being elucidated. This process has been facilitated by laboratory based studies in which animals receive either a single dose of ethanol (acute studies) or a continuous supply of ethanol in their daily diets (chronic studies). Results from these models show that acute ethanol dosage causes a marked decrease in the synthesis of contractile proteins. This occurs in the absence of overt mitochondrial abnormalities: ATP concentrations are generally unaffected. Paradoxically, the synthesis of mitochondrial proteins is reduced. Use of metabolic inhibitors suggests that the deleterious effects of acetaldehyde contribute to these reductions in protein synthesis. In chronic studies, ethanol causes a reduction in the amount of contractile proteins, and two dimensional protein profiling implicates selective loss of individual myocardial proteins. The differential activities of lysosomal proteases may contribute to this patterned response. However, in chronic ethanol feeding, adaptive mechanisms also become important, as the synthesis of the myofibrillary proteins increases. Overall, the mechanisms inherent in these biochemical responses may contribute to the genesis of a distinct disease entity, alcoholic heart muscle disease.

Multidrug-resistant tuberculous meningitis in KwaZulu-Natal, South Africa.

Multidrug-resistant (MDR) pulmonary tuberculosis (TB) is well described in the literature. Reports of MDR TB meningitis (MDR-TBM), however, are limited to case reports and a single case series. During the period of 1999-2002, 350 patients with TBM were identified by cerebrospinal fluid culture for TB. Thirty patients (8.6%) had TB that was resistant to at least isoniazid and rifampicin. All 30 patients were included in this study. We reviewed hospital charts of the patients with MDR-TBM and describe our experience. Seventeen patients with MDR-TBM died, and, of those who were known to be alive, many experienced significant morbidity. Eighteen patients were HIV positive. Twenty-two patients had been treated for TB in the past, 3 patients had received no previous treatment for TB, and the history of TB treatment was unknown for 5 patients. The study highlights the prevalence of MDR-TBM and identifies new challenges in the management of affected patients.

Oxidants, antioxidants and alcohol: implications for skeletal and cardiac muscle.

The chronic form of alcoholic skeletal myopathy is characterized by selective atrophy of Type II fibers and affects up to two thirds of all alcohol misusers. Plasma selenium and alpha-tocopherol are reduced in myopathic alcoholics compared to alcoholic patients without myopathy. Plasma carnosinase is also reduced in myopathic alcoholics, implicating a mechanism related to reduced intramuscular carnosine, an imidazole dipeptide with putative antioxidant properties. Together with the observation that alcoholic patients have increased indices of lipid peroxidation, there is evidence suggestive of free radical (i.e., unpaired electrons or reactive oxygen species) mediated damage in the pathogenesis of alcohol-induced muscle disease. Protein synthesis is a multi-step process that encompasses amino acid transport, signal transduction, translation and transcription. Any defect in one or more of the innumerable components of each process will have an impact on protein synthesis, as determined by radiolabelling of constituent proteins. Both acute and chronic alcohol exposure are associated with a reduction in skeletal muscle protein synthesis. Paradoxically, alcohol-feeding studies in rats have shown that the imidazole dipeptide concentrations are increased in myopathic muscles though alpha-tocopherol contents are not significantly altered. In acutely dosed rats, where protein synthesis is reduced, protein carbonyl concentrations (an index of oxidative damage to muscle) also decline slightly or are unaltered, contrary to the expected increase. Alcoholic cardiomyopathy can ensue from heavy consumption of alcohol over a long period of time. The clinical features include poor myocardial contractility with reduced left ventricular ejection volume, raised tissue enzymes, dilation of the left ventricle, raised auto- antibodies and defects in mitochondrial function. Whilst oxidant damage occurs in experimental models, however this issues remains to be confirmed in the clinical setting. In the rat, circulating troponin-T release increases in the presence of ethanol, a mechanism ascribed to free radical mediated damage, as it is prevented with the xanthine oxidase inhibitor and beta-blocker, propranolol. However, whilst propranolol prevents the release of troponin-T, it does not prevent the fall in whole cardiac protein synthesis, suggestive of localized ischemic damage due to ethanol.

Alcohol and the myocardium.

Structural and functional abnormalities are prominent in alcoholic cardiomyopathy (ACM). Histological features in affected subjects are almost identical to the characteristics of dilated cardiomyopathy. Quantitative morphometry, however, can distinguish between ACM and dilated cardiomyopathy. Biopsies from patients with ACM show increases in the activities of some myocardial enzymes (alpha-hydroxybutyric dehydrogenase, creatine kinase, lactate dehydrogenase, malic dehydrogenase) which are correlated with the bimodal distribution of alcohol intake and may represent an adaptive response. One-third of patients with ACM have serum antibodies against cardiac acetaldehyde-protein adducts. Animal models of ethanol toxicity have shown that acutely, alcohol and acetaldehyde reduce the synthesis of cardiac contractile proteins in vivo. Two-dimensional SDS-PAGE has also shown that in rats chronically fed alcohol, the relative amounts of over 10% of heart muscle proteins are altered. The heat shock proteins (HSP) Hsp60 and Hsp70 are decreased in alcohol-fed rats, as is desmin. Reduction in HSPs may indicate reduced myocardial protection whilst a fall in desmin may indicate structural defects. In conclusion, ACM is a complex process that is due to altered protein synthesis, the formation of acetaldehyde adducts and a reduction of cardiac HSPs and desmin. Both acetaldehyde and alcohol are myocardial perturbants.

Anomalous coronary artery, aortic dissection, and acute myocardial infarction.

The combination of acute coronary occlusion and aortic dissection because of involvement of one or other coronary vessels in the dissection flap is uncommon. Furthermore, the occurrence of an anomalous coronary artery and its involvement in acute myocardial infarction is even more uncommon. We describe a patient with acute myocardial infarction in whom an acute aortic dissection involved the ostium of an anomalous circumflex artery.

Inability of propranolol to prevent alcohol-induced reductions in cardiac protein synthesis in vivo.

Rats were acutely injected with alcohol (75 mmol/kg body weight) and at the end of 2.5 h changes in cardiac synthesis rates were assessed with a 'flooding dose' of L-[4-(3)H]phenylalanine. The results showed that acute alcohol dosage reduced the fractional rates of cardiac protein synthesis (k(S), %/day). This effect was also seen when data were expressed relative to either RNA (i.e. k(RNA), mg protein/day/mg RNA) or DNA (i.e. k(DNA), mg protein/day/mg DNA). Both left and right ventricles responded similarly to ethanol. However, propranolol pre-treatment (at doses of 17 and 170 micromol/kg body weight; i.p.) did not prevent these effect of ethanol in either the left or right ventricle. Indeed, there was evidence that propranolol per se perturbed cardiac protein synthesis in vivo in control (i.e. without ethanol) rats particularly in the right ventricle. In conclusion, the results suggest that alcohol is cardiotoxic to the myocardium, which may cause its effects on protein synthesis independently of beta-receptors and/or xanthine oxidase inhibition.

Non-cardiac nucleic acid composition and protein synthesis rates in hypertension: studies on the spontaneously hypertensive rat (SHR) model.

Various studies have shown the involvement of extracardiac tissues in hypertension, including the hepato-intestinal tract, musculo-skeletal system, skin, and the kidney. It was our hypothesis that these perturbations in non-cardiac tissues would also include alterations in protein metabolism. Thus, the reported differences in soleus contractile protein composition may be related to changes in muscle protein synthesis or reduced protein synthetic efficiencies. The aim of the present study was to characterise tissue composition of nucleic acids and rates of protein synthesis in non-cardiac tissues, such as liver, skeletal muscle (i.e., the Type I fibre-predominant soleus and Type II fibre-predominant plantaris), kidney, bone (tibia), skin and the gastrointestinal tract in a genetic model of hypertension (i.e., spontaneously hypertensive rats (SHRs), 15 weeks old) compared to their genetic aged-matched counterparts, i.e., normotensive Wistar-Kyoto (WKY) controls. Rates of protein synthesis were measured in vivo after injection with a flooding dose of L-[4-(3)H]phenylalanine. The results showed changed tissue wet weights (g per organ) for plantaris (+10%, P<0.05), liver (+25%, P<0.01), brain (-9%, P<0.01), jejunum (+39%, P<0.001) and tibia (+17%, P<0.001) in SHRs compared to WKY controls. Protein content (g or mg per organ) was increased in the liver (+32%, P<0. 01) and tibia (+37%, P<0.05). RNA contents (mg per organ) were increased in plantaris (+17%, P<0.01), liver (+22%, P<0.01) and jejunum (+11%, P<0.05). DNA (mg per organ) was increased in plantaris (+16%, P<0.025) and jejunum (+12%, P<0.025). The protein synthetic capacities (i.e., C(s), mg RNA/g protein) were higher in soleus (+41%, P<0.01) and plantaris (+6%, P<0.05) muscles of SHRs compared to WKYs, whereas values were lower in liver (-11%, P<0.01) and kidney (-6%, P<0.01) of SHRs compared to WKYs. The fractional rate of protein synthesis (i.e., k(s), the percentage of the protein pool renewed each day) was not significantly different for any of the tissues, though the rate of protein synthesis per unit RNA (i.e., k(RNA), mg protein/day per mg RNA) was reduced in the soleus (-24%, P<0.05) and the synthesis rate per unit DNA, i.e., k(DNA) (mg protein/day per mg DNA) was increased in the tibia (+31%, P<0.025). This is the first report of significant differences between indices of protein metabolism in extracardiac tissues in hypertension, which may reflect endocrine factors and/or the systemic influence of hypertension per se.

Effects of lisinopril and amlodipine on antioxidant status in experimental hypertension.

The objective of this investigation was to compare changes in antioxidant status (together with other metabolites relevant to hypertension) in plasma and cardiac tissue from spontaneously hypertensive rats (SHR) and normotensive Wistar Kyoto rats (WKY), following 8 weeks of treatment with lisinopril (angiotensin converting enzyme inhibitor) or amlodipine (Ca(2+) channel antagonist) respectively. There was no significant difference in the levels of total antioxidant capacity, retinol, urea, albumin or triglyceride in plasma from SHR or WKY rats, with or without lisinopril or amlodipine treatment. However in SHR rats, levels of alpha-tocopherol were substantially reduced in both plasma (-54% WKY, P<0.01) and cardiac tissue (-43% WKY, P<0.05). Treatment with lisinopril ameliorated reduced levels of plasma alpha-tocopherol in SHR rats, but not in cardiac tissue. Amlodipine treatment had no effect on alpha-tocopherol levels in plasma or cardiac tissue in SHR rats. In SHR rats total cholesterol levels were significantly lower thanWKY controls (-36%, P<0.001). This effect was reversed in lisinopril treated SHR rats (+27%, P<0.01). Plasma high density lipoprotein (HDL) and low density lipoprotein (LDL) cholesterol were reduced in untreated SHR rats (P<0.025) when compared to WKY controls; neither lisinopril nor amlodipine treatment significantly altered these parameters. These findings suggest possible alternative mechanisms of action for lisinopril, and reinforce its use in hypertensive patients or patients with left ventricular hypertrophy.

Poor regression of myocardial hypertrophy following concomitant chronic alcohol ingestion and angiotensin converting enzyme (ACE) inhibition.

In the following study we examined the combined effect of chronic alcohol administration and anti-hypertensive drug treatment in spontaneously hypertensive rats (SHR). SHR were fed alcohol for six weeks while taking the angiotensin converting enzyme (ACE) inhibitor lisinopril. After six weeks, protein synthesis rates, contractile protein levels and protease activities were examined in control; alcohol; control+lisinopril; alcohol+lisinopril groups. Lisinopril treatment significantly reduced left ventricular mass, protein content and contractile proteins in control rats, but these effects were not as pronounced in alcohol+lisinopril rats. Protein synthesis rates in both mixed and myofibrillar fractions were not significantly different in any of the 4 groups. The enzyme activities of the proteases cathepsin D and dipeptidyl aminopepetidase I increased in control+lisinopril rats, however, this effect was not evident in alcohol+lisinopril rats. Contractile proteins identified by one-dimensional electrophoresis showed that lisinopril treatment reduced all contractile proteins in control rats. However, in alcohol+ lisinopril rats, myosin heavy chain was higher than in control+lisinopril rats. In summary, alcohol ingestion impairs the regression of the hypertrophic myocardium in SHR on ACE-inhibitor treatment, which was reflected by altered protein metabolism. This study suggests that successful anti-hypertensive treatment may not be achieved if alcohol misuse is evident.

Effects of the dihydropyridine calcium channel blocker amlodipine on ventricular and atrial protein synthesis in an aortic constriction model of hypertension and, following chronic treatment, in the left ventricle of SHR rats.

The dihydropyridine calcium channel blocking agent amlodipine is an effective anti-hypertensive agent and its use (in doses of 5 or 10 mg/day/kg body weight) was investigated in male Wistar rats with hypertension induced by aortic constriction. Controls were sham-operated and pair-fed. At the end of the study, rates of protein synthesis were measured with radiolabelled phenylalanine to calculate fractional rates of protein synthesis (ks), absolute rates of protein synthesis (Vs) and synthesis rates relative to RNA (kRNA). After 30 days of aortic constriction, weights of the left ventricle and left atrium were significantly increased by hypertension. The weights of the right ventricle and right atrium were relatively unaffected. Hypertension was accompanied by significant increases in the protein and RNA contents of the left ventricle and left atrium. The contractile and non-contractile protein contents were also increased in the left ventricles of hypertensive rats as were total proteins and total RNA. In the myofibrillary fraction, ks decreased. The right ventricle and right atrium were generally unaffected except for a decline in mixed protein ks. Many of these changes in hypertension were ameliorated by treatment with amlodipine, particularly at the higher dose (i.e. 10 mg/kg body weight/day) implicating an effect on protein metabolism. In the left ventricle these included amelioration of the increases in mixed and contractile proteins, total RNA contents, mixed Vs and Vs for sarcoplasmic and stromal proteins. The ameliorating effects of amlodipine were moderate in the left atrium. Furthermore, amlodipine also retarded the hypertension-induced reduction in right ventricule rates of protein synthesis. Although the preceding study emphasises the preventative aspects of amlodipine's efficacy, an additional study was carried out in SHR rats to ascertain the applicability for regression per se. Amlodipine (10 mg/kg/body weight) therapy for 30 weeks caused regression of LV mass, total protein, RNA and DNA contents. We conclude that amlodipine, is an efficient agent in ameliorating the hypertension-induced changes in protein metabolism in an aortic constriction model.

Protein synthesis in the heart in vivo, its measurement and patho-physiological alterations.

Changes in cardiac protein composition occur in a variety of patho-physiological situations and are usually accompanied by modifications in protein synthesis. Although adjustments in protein synthesis during starvation may be adaptive, the alterations in protein synthesis seen in response to ethanol ingestion may be pathological and an important step in the genesis of alcoholic heart muscle disease. The alterations in heart muscle in hypertension are initially adaptive but in the long term they are deleterious, and involve both transcription and translation. While adequate methods exist for quantifying the amount of mRNA for contractile and non-contractile proteins, such studies of gene-expression provide no dynamic information on the rate at which tissue proteins are lost or accrued. This can only be determined by measuring the rate of protein turnover, i.e. either protein synthesis or protein breakdown. Techniques for directly determining the rates of protein breakdown are limited or involve surgical procedures. Methods for measuring the rate of protein synthesis are described, and are illustrated by their application to the investigation of starvation and ethanol toxicity. In particular, attention is focused on the fact that reliable rates of protein synthesis are obtained only if the specific radioactivity of the precursor at the site of protein synthesis (aminoacyl-tRNA) is assessed.