Cellular and molecular immune response and production performance of Indian white shrimp Penaeus indicus (H. Milne-Edwards, 1837), reared in a biofloc-based system with different protein levels of feed

The present study focuses on the immunity and growth of Penaeus indicus fed with varying protein levels (25%, 30%, and 35%) in a biofloc based rearing system. A 120 days growth trial was carried out using juvenile Penaeus indicus (0.71 ± 0.01) with dietary protein level, 25% (LP), 30% (MP), and 35% (HP), and a control diet-fed with 35% acted as control group resulting in 4 treatments each with four replicates and were randomly assigned 16 tank units (7500 L each). A combination of different carbon sources (molasses, wheat flour, and rice bran in 2:1:1 ratio), yeast and a probiotic (Bacillus sp.) consortium were used for the development of biofloc. At the end of the trial, the growth parameters of shrimps viz., initial weight, feed conversion ratio (FCR), and daily growth coefficient (DGC) were computed. The results indicated that shrimp fed with medium (30%) protein (MP) diet recorded significantly (P < 0.05) improved growth performance compared to high protein fed group (35%) and low protein (25%) fed group (LP) in a biofloc system and control group (35%). The immunological parameters such as hemagglutination activity (HA) assay, serum protein, lysozyme, phenol oxidase (PO), and inhibition of superoxide dismutase (SOD) activity were observed in serum, plasma, and hemocyte lysate supernatant (HLS). The HA activity, PO activity in plasma was found to be higher in high protein fed animals, whereas medium protein resulted in enhanced PO activity in serum. Similarly, lysozyme and SOD were inhibited well in high protein fed animals compared to the low protein fed group. The vital immune genes's mRNA profiling showed a potential rise in the expressional pattern in MP and HP treatments compared to LP and control. BGBP (beta-1,3-glucan binding protein) and hemocyanin mRNA transcript levels were highly upregulated in the HP (5 fold) and moderately expressed in MP (2 fold) and LP (1-2 fold). The transcripts of peroxinectin, antimicrobial peptides like crustin showed significant upregulation in HP followed by in MP and LP and control. Likewise, other immune genes, such as SOD, prophenoloxidase (proPO), showed a similar trend in a marginal way, indicating immunomodulation in the biofloc groups. This study suggested that biofloc with high protein (35%) supplementation can substantially enhance the immune response of shrimps, although medium protein level (30%) is optimum for improving the survival, growth, and in turn economic return in Indian white shrimp.

Peste Des Petits Ruminants in Atypical Hosts and Wildlife: Systematic Review and Meta-Analysis of the Prevalence between 2001 and 2021

Peste des petits ruminants (PPR) or goat plague is considered a leading, highly contagious, and most lethal infectious viral disease of small ruminants affecting the worldwide livestock economy and international animal trade. Although sheep and goats are the primarily affected, the PPR Virus (PPRV) host range has expanded to other livestock (large ruminants) and wildlife animals over the last few decades, resulting in serious concern to the ongoing PPR global eradication program, which is primarily optimized, designed, and targeted towards accessible sheep and goat population. A systematic review and meta-analysis study was conducted to estimate the prevalence and spill-over infection of PPRV in large ruminants (bovine and camel) and wildlife. Published articles from 2001 to October 2021 on the "PPR" were searched in four electronic databases of PubMed, Scopus, Science direct, and Google Scholars. The articles were then selected using inclusion criteria (detection/prevalence of PPRV in bovine, camel, and wildlife population), exclusion criteria (only sheep or goats, lack of prevalence data, experimental trial, test evaluation, and reviews written in other languages or published before 2001), and the prevalence was estimated by random effect meta-analysis model. In the current study, all published articles belonged to Africa and Asia. The overall pooled prevalence of PPR estimates was 24% (95% CI: 15-33), with 30% in Asia (95% CI: 14-49) and 20% in Africa (95% CI: 11-30). The overall estimated pooled prevalence at an Africa-Asia level in bovine and camel was 13% (95% CI: 8-19), and in wildlife, it was 52% (95% CI: 30-74) with significant heterogeneity (I² = 97%) in most pooled estimates with a high prevalence in atypical hosts and wildlife across Asia and Africa. Over the last two decades, the host range has increased drastically in the wildlife population, even for prevalent PPR in the unnatural hosts only for a short time, contributing to virus persistence in multi-host systems with an impact on PPR control and eradication program. This observation on the epidemiology of the PPRV in unnatural hosts demands appropriate intervention strategies, particularly at the livestock-wildlife interface.

Pathological evaluation for sterilization of routinely used prosthodontic and endodontic instruments

Background:

In daily practice of dentistry, we use same instruments on many patients. Before use, all instruments must be cleaned, disinfected, and sterilized to prevent any contamination. Pre-cleaning and sterilization of some devices can be difficult because of their small size and complex architecture. Dental burs and endodontic files are such instruments. Dental burs come in a variety of shapes and sizes, all with highly complex and detailed surface features.

Aim:

To determine the effectiveness of various disinfectants and sterilization techniques for disinfection and resterilization of dental burs and endodontic files.

Materials and Methods:

The materials used for the study were dental burs and endodontic files. Disinfectants used were Quitanet plus, glutaraldehyde, glass-bead sterilizer, and autoclave. The sterility of used dental burs and endodontic files was analyzed. Burs and files that had been used were pre-cleaned, resterilized, and then tested for various pathogens. Each item was transferred by sterile technique into Todd-Hewitt broth, incubated at 37°C for 72 h, and observed for bacterial growth.

Results:

The present study shows that the endodontic files and burs sterilized by autoclaving and glutaraldehyde showed complete sterilization. Burs and files immersed in glutaraldehyde (2.4%) for 12 h showed complete sterilization, whereas Quitanet plus solution and glass-bead sterilizer showed incomplete sterilization.

Conclusion:

The present study results indicate that autoclaving and glutaraldehyde (2.4%) showed complete sterilization. Other methods cannot be relied upon for sterilization.

Fungal peritonitis in continuous ambulatory peritoneal dialysis: The impact of antifungal prophylaxis on patient and technique outcomes

Fungal peritonitis (FP) is a rare, but serious complication of peritoneal dialysis. We analyzed the incidence of FP, associated risk factors and outcome of patients with FP and evaluated the role of prophylactic antifungal agent in reducing its incidence. We studied all patients with FP from January 2005 to January 2012. Study period was divided into two parts, period I (January 2005 to January 2010), when prophylactic antifungal was not used and period II (January 2010 to January 2012), when prophylactic antifungal (fluconazole) was used. A total of 142 episodes of peritonitis were documented during this period of which 20 (14%) were FP. During the study period I, 18 of 102 episodes of peritonitis (17.6%) and in the study period II (with antifungal prophylaxis), only 2 of 40 episodes of peritonitis (5%) were due to fungal infection (P = 0.04). Nine out of 20 patients (45%) had prior exposure to antibiotics. Fungal isolates were Candida albicans in 65%, non-albicans Candida in 25%, Rhizopus species in 5% and Alternaria in 5% of the patients. While 12 out of 20 patients (60%) recovered completely and were re-initiated on continuous ambulatory peritoneal dialysis (CAPD), 4 of them expired (20%) and 4 others (20%) were shifted to hemodialysis. Use of prophylactic antifungal agent significantly reduced the incidence of FP (P = 0.04). We conclude that - fluconazole when used as a prophylactic agent in the setting of bacterial peritonitis significantly reduces the incidence of subsequent FP in CAPD patients.

Protective effect of CardiPro against doxorubicin-induced cardiotoxicity in mice

The effect of CardiPro, a polyherbal formulation, with an antioxidant property, has been studied on doxorubicin (DXR)-induced cardiotoxicity in mice. CardiPro (150 mg/kg b.w., twice daily was administered orally for 7 weeks along with four equal injections (each containing 4.0 mg/kg b.w., DXR) intraperitoneally, once weekly (cumulative dose 16 mg/kg). After a 3-week post DXR treatment period, cardiotoxicity was assessed by noting mortality, volume of ascites, liver congestion, changes in heart weight, myocardial lipid peroxidation, antioxidant enzymes and histology of heart. DXR-treated animals showed higher mortality (50%) and more ascites. Myocardial SOD and glutathione peroxidase activity were decreased and lipid peroxidation was increased. Histology of heart of DXR-treated animals showed loss of myofibrils and focal cytoplasmic vacuolization. CardiPro significantly protected the mice from DXR-induced cardiotoxic effects as evidenced by lower mortality (25%), less ascites, myocardial lipid peroxidation, normalization of antioxidant enzymes and minimal damage to the heart histologically. Our data confirm the earlier reports that DXR cardiotoxicity is associated with the free radical-induced tissue damage. Administration of CardiPro, with an antioxidant property, protected the DXR-induced cardiotoxicity in mice.

Anaesthetic and intensive care aspects of spinal injury

Over the last few years, spinal injuries have been classified depending upon their causative mechanism and on the basis of three column concept of the structure of vertebral column. The concept of primary and secondary injury has laid more stress on prevention and treatment of secondary injury. Methyl prednisolone still remains the drug of choice for prevention of secondary injury. Spinal injury involves all organ systems of the body depending on the level of lesion. Immobilisation of injured spine and maintenance of adequate airway after spinal injury need immediate attention. Orotracheal intubation under general anaesthesia, with manual in-line traction, is still considered the best method. Hypotension, hypertension and hyperglycaemia should be avoided during anaesthesia. Care should be taken to avoid effects of autonomic hyper reflexia. Spinal cord functions should be monitored and, if required, induced hypotension can be used with adequate monitoring.

A study on clinical profile of falciparum malaria in a tertiary care hospital in south India

Malaria continues to be a major problem in tropical countries. To study the clinical features and complications of malaria in a tertiary care hospital in south India, records of 183 patients were analysed. Among 86 patients with P. falciparum and mixed infection, 24 (28 per cent) had cerebral malaria and 32 (37 per cent) had hyperbilirubinemia. Twenty-three out of 32 (72 per cent) patients with jaundice had direct hyperbilirubinemia and elevated liver enzymes suggesting hepatocellular damage. Mortality of the order of 10 per cent was seen only in P. falciparum malaria. High incidence of hepatic involvement and hepatorenal failure were the unusual features observed in the study.

Oxidant stress and essential fatty acids in patients with risk and established ARDS

Oxygen free radicals are important mediators of both physiological and pathological events. In acute lung injury, the activated lymphocytes stimulate tumor necrosis factor (TNF) and other cytokines. These lymphokines augment free radical generation by polymorphonuclear leukocytes (PMNLs), macrophages and other cells which may ultimately produce acute respiratory distress syndrome (ARDS). This is supported by our results presented here in that there is a significant increase in lipid peroxidation products in patients with established ARDS. The amount of lipid peroxidation was significantly higher in the established ARDS group compared to patients who are at risk for ARDS. Nitric oxide concentrations were significantly decreased in established ARDS compared to the control and those who are at risk for ARDS. Fatty acid analysis of the plasma phospholipid fraction revealed a significant decreased in linoleic acid, gamma-linolenic acid, dihomo-gamma-linolenic acid and arachidonic acid levels of n-6 series and alpha-linolenic acid, eicosapentaenoic acid, docosa-hexanenoic acid of n-3 series. Patients who are at risk for ARDS have decreased levels of gamma-linolenic acid of the n-6 series, alpha-linolenic acid and eicosapentaenoic acid of the n-3 series. These results suggest that lipid peroxides and alteration in essential fatty acid metabolism may have a role in the pathogenesis of ARDS.

Melatonin, a pineal hormone with antioxidant property, protects against gentamicin-induced nephrotoxicity in rats

The present study investigated the effects of melatonin, an antioxidant, on gentamicin-induced nephrotoxicity in rats. Melatonin (5 mg/kg p.o.) was used 3 days before and 8 days simultaneously with gentamicin (80 mg/kg i.p.) Saline-treated animals served as controls. Determinations of urinary creatinine, N-acetyl-beta-D-glucosaminidase, glucose, protein, blood urea, serum creatinine, plasma and kidney tissue malondialdehyde (MDA), and antioxidant enzyme levels in kidney tissue were done after 8 days of gentamicin treatment. The kidneys were also examined for morphological changes using histological techniques. Gentamicin caused nephrotoxicity as evidenced by marked elevation in blood urea and serum creatinine. Mean blood urea and serum creatinine levels were 289+/-50, and 2.5+/-0.5 mg/dl, respectively, in rats treated with gentamicin. Melatonin significantly protected the rats from gentamicin-induced nephrotoxicity; blood urea and serum creatinine levels were 23+/-2.7 and 0.88+/-0.19 mg/dl, respectively. The creatinine clearance was decreased with gentamicin treatment (0.048+/- 0.007 ml/min) as compared with controls (0.41+/-0.08 ml/h/kg). In rats treated with melatonin plus gentamicin, the creatinine clearance was similar to controls (0.41+/-0.08 ml/h/kg). The product of lipid peroxidation (MDA) was markedly increased in plasma (2.10+/-0.15 nmol) and kidney tissue (8.87+/-3.2 nmol/mg protein) with gentamicin treatment. Melatonin prevented the gentamicin-induced rise in plasma MDA (1.03+/-0.27 nmol) and kidney tissue MDA (2.57+/-0.87 nmol/mg protein). An increased excretion of urinary N-acetyl-beta-D-glucosaminidase, glucose, and protein by gentamicin was also prevented by melatonin. Kidneys from gentamicin-treated rats showed tubular epithelial loss with intense granular degeneration involving more than 50% of renal cortex, while there were findings comparable to controls in melatonin plus gentamicin treated rats. The present study indicates that melatonin significantly protects against gentamicin-induced renal toxicity in Wistar rats.

Cytotaxonomic evidence for the presence of Anopheles nivipes in India

Anopheles philippinensis mosquitoes were collected from 5 states in India: Assam, Meghalaya, Arunachal Pradesh, Manipur, and Nagaland. Half-gravid females were examined for variations in wing venation using the presector dark mark on vein I and polytene chromosomes derived from ovarian nurse cells. Polytene chromosomes were examined for diagnostic inversions, t on chromosome arm 2 and I on arm 5. Based on wing characteristics, both An. philippinensis and An. nivipes were identified. Polytene chromosome examinations revealed that all specimens from these 2 populations had 2t; 51 inversion genotype, a diagnostic character for An. nivipes. The wing character was not diagnostic; therefore, it was concluded that all the specimens examined were actually An. nivipes and not An. philippinensis. Further, the X chromosome was of x+b type, that is, the standard arrangement with reference to the inversion b, reported in the An. nivipes population in Thailand. This is the 1st report that unequivocally establishes the occurrence of An. nivipes in India and also shows that the adult wing character is not reliable in distinguishing An. philippinensis from An. nivipes, as has been observed in Thailand.

Ginkgo biloba extract ameliorates gentamicin-induced nephrotoxicity in rats

The effect of Ginkgo biloba (EGb), a plant extract with an antioxidant effect, has been studied on gentamicin-induced nephrotoxicity in male wistar rats. Ginkgo biloba extract (300 mg/kg BW) was administered orally 2 days before and 8 days concurrently with gentamicin (80 mg/kg BW). Saline treated animals served as control. Estimations of urine creatinine, glucose, blood urea, serum creatinine, plasma and kidney tissue MDA were carried out after 8 days of gentamicin treatment. Kidneys were examined using histological techniques. Blood urea and serum creatinine were increased by 896% and 461% respectively, with gentamicin, compared to saline treated group. Creatinine clearance was significantly decreased with gentamicin. Ginkgo biloba extract protected rats from gentamicin-induced nephrotoxicity. Changes in blood urea, serum creatinine and creatinine clearance induced by gentamicin were significantly prevented by Ginkgo biloba extract. There was a 177% and 374% rise in plasma and kidney tissue MDA with gentamicin, which were significantly reduced to normal with Ginkgo biloba extract. Histomorphology showed necrosis and desquamation of tubular epithelial cells in renal cortex with gentamicin, while it was normal and comparable to control with Ginkgo biloba extract. These data suggest that supplementation of Ginkgo biloba extract may be helpful to reduce gentamicin nephrotoxicity.

Carvedilol: a beta blocker with antioxidant property protects against gentamicin-induced nephrotoxicity in rats

Gentamicin is an antibiotic effective against gram negative infections, whose clinical use is limited by its nephrotoxicity. Since the pathogenesis of gentamicin-induced nephrotoxicity involves oxygen free radicals, the antioxidant carvedilol may protect against gentamicin-induced renal toxicity. We therefore tested this hypothesis using a rat model of gentamicin nephrotoxicity. Carvedilol (2 mg/kg) was administered intraperitoneally 3 days before and 8 days concurrently with gentamicin (80 mg/kg BW). Estimations of urine creatinine, glucose, blood urea, serum creatinine, plasma and kidney tissue malondialdehyde (MDA) were carried out, after the last dose of gentamicin. Kidneys were also examined for morphological changes. Gentamicin caused marked nephrotoxicity as evidenced by increase in blood urea, serum creatinine and decreased in creatinine clearance. Blood urea and serum creatinine was increased by 883% and 480% respectively with gentamicin compared to control. Carvedilol protected the rats from gentamicin induced nephrotoxicity. Rise in blood urea, serum creatinine and decrease in creatinine clearance was significantly prevented by carvedilol. There was 190% and 377% rise in plasma and kidney tissue MDA with gentamicin. Carvedilol prevented the gentamicin induced rise in both plasma and kidney tissue MDA. Kidney from gentamicin treated rats, histologically showed necrosis and desquamation of tubular epithelial cells in renal cortex, whereas it was very much comparable to control with carvedilol. In conclusion, carvedilol with its antioxidant property protected the rats from gentamicin-induced nephrotoxicity.

Effect of pentoxifylline on cyclosporine-induced nephrotoxicity in rats

Effect of unique hemorrheologic agent pentoxifylline (PTX) was investigated on cyclosporine (CsA) induced nephrotoxicity in rats. Compared to saline control, CsA produced significant increase in blood urea and serum creatinine. Pentoxifylline treatment prevented the CsA-induced rise in blood urea and serum creatinine. Creatinine clearance (Ccr) and lithium clearance (Licr) was decreased with CsA. PTX treatment prevented the CsA-induced decrease in Ccr and Licr. Malondialdehyde (MDA) was increased with CsA compared to saline treated animals. PTX prevented the CsA-induced MDA rise. Kidney form CsA treated rat showed marked vacuolar degeneration of tubular epithelium with excess of microcalcification. Severity of the lesions was markedly reduced in rats treated with PTX plus CsA. The results indicate that PTX reduces CsA-induced renal toxicity in rats.

Melatonin: an antioxidant protects against cyclosporine-induced nephrotoxicity

BACKGROUND

Cyclosporine (CsA) causes a dose-related decrease in renal function in experimental animals. Different mediators for CsA nephrotoxicity have been suggested; oxygen free radicals are one of them. In experimental model of Wistar rats, the role of antioxidant melatonin (Mel), the main product of pineal secretion, was investigated in CsA nephrotoxicity.

METHODS

Male Wistar rats were divided into four groups: saline control, 50 mg/kg CsA, 500 microg/kg Mel, and CsA + Mel. At the end of 14th day of treatment, blood urea, creatinine, malondialdehyde, and creatinine and lithium clearance were estimated. Histopathological examination of kidney from all the groups was performed.

RESULTS

CsA caused marked elevation in blood urea, serum creatinine, and plasma malondialdehyde and a decrease in creatinine and lithium clearance. Mel significantly antagonized CsA-induced renal impairment. Microcalcification in corticomedullary junction seen with CsA was prevented by Mel.

CONCLUSION

These results indicate that Mel, through its antioxidant properties, provides protection against CsA-induced nephrotoxicity.

Lacidipine protects against cyclosporine-induced nephrotoxicity in rats

The effect of lacidipine (LA), a new calcium channel blocker with an antioxidant effect, has been studied on cyclosporine (CsA)-induced nephrotoxicity in male Wistar rats. Lacidipine (1 mg/kg BW) was administered orally 3 days before and 14 days concurrently with CsA (50 mg/kg BW orally). Urine volume, Na+, K+, Li+ and creatinine in urine, and blood urea, serum creatinine, lithium, plasma malondialdehyde (MDA) and CsA levels were estimated in blood after 14 days CsA treatment. Kidneys were examined using histological techniques. Blood urea and serum creatinine were increased by 305 and 211%, respectively, with CsA when compared to the saline-treated animals. Creatinine clearance (Ccr) and lithium clearance (Licr) were decreased and proximal tubule fractional reabsorption 1-(Licr/Ccr) was significantly increased with CsA. Lacidipine protected rats from CsA-induced nephrotoxicity. Changes in blood urea, serum creatinine, Ccr, Licr and proximal tubule fractional reabsorption induced by CsA were significantly prevented by LA. There was a 160% rise in MDA levels with CsA, which was significantly reduced equal to control with LA. Histomorphology showed microcalcification with CsA, while it was normal with LA. In rats treated with LA, CsA did not show any microcalcification. Our data suggest that supplementation of LA may be helpful to reduce CsA nephrotoxicity.

Comparison of methods of eye protection under general anaesthesia

PURPOSE

To compare and assess the efficacy of eye ointment and adhesive tape for protection of eyes under general anaesthesia.

METHODS

One hundred and fifty patients (300 eyes) undergoing general anaesthesia for > 90 min for non-ophthalmic procedures were divided randomly into three groups (C, T & O). Eyes in group C were left as control, in group T hypoallergen tape was applied and in group O chloromycetin ointment was used. In all eyes basal tear production and visual acuity was assessed and corneal examination was carried out after fluorescein staining both before and after surgery. All the patients were subjected to a conventional general anaesthesia technique.

RESULTS

General anaesthesia reduced basal tear production irrespective of the method of eye protection used (P < 0.0001). The overall incidence of corneal epithelial defects was 10%, of which 90% occurred in the control group, 6.6% in the tape and 3.3% in the ointment group. There was no difference between pre and post operative visual acuity (P : NS). Corneal injuries were more common in the dependent eye in the lateral position and the incidence of corneal epithelial defects did not alter with increase in duration of surgery.

CONCLUSION

During general anaesthesia eyes need protection either by tape or ointment as incidence of corneal injuries is greater in unprotected eyes.

Effect of cis-unsaturated fatty acids, prostaglandins, and free radicals on angiotensin-converting enzyme activity in vitro

Angiotensin-converting enzyme (ACE) is known to play an important role in the pathobiology of human essential hypertension. Similarly, cis-unsaturated fatty acids, prostaglandins, and free radicals are believed to play a role in the control of blood pressure. It was observed that all the cis-unsaturated fatty acids tested can inhibit ACE activity to a significant degree. On the other hand, prostaglandins and free radicals, superoxide anion, hydrogen peroxide, and hydroxyl radical did not show significant inhibitory effects on ACE activity in vitro. But, the nitric oxide donor sodium nitroprusside showed a potent inhibitory action on ACE activity, suggesting that one of the possible mechanism(s) by which nitric oxide can bring about its anti-hypertensive action might be by modulating ACE activity in addition to its direct vasodilator action. These results indicate that there is a close interaction among ACE activity, cis-unsaturated fatty acids, and nitric oxide, which may have relevance to the pathobiology of human essential hypertension.

A probabilistic model of hypobaric decompression sickness based on 66 chamber tests

One consequence of the NASA tissue ratio (TR) model is that calculated probability of decompression sickness [P(DCS)] is constant in tests at different ambient pressures so long as the ratio of P1N2 to P2 is the same in each test; P1N2 is N2 pressure in the 360 minute half-time compartment, and P2 is ambient pressure after decompression. We test the hypothesis that constant P(DCS) is better described by TRs that decrease as P2 decreases. Data were from 66 NASA and USAF hypobaric chamber tests resulting in 211 cases of DCS in 1075 exposures. The response variable was presence or absence of DCS while at P2. Explanatory variables were P1N2, P2, exercise at P2, (yes or no), time to DCS (failure time), and time to end of test in those without DCS (censored time). Probability models were fitted using techniques from survival analysis. The log likelihood for the two parameter log logistic survival model was -846 with only failure and censored times, -801 when TR [P1N2/P2] plus exercise were added, and -663 when modified TR [(((P1N2+cl)/P2)-1)c2] plus exercise were added, where c1 and c2 are fitted parameters in the five parameter model. Constant P(DCS) was better described by TRs that decrease as P2 decreases; a conclusion supported by additional empirical observations, and bubble growth models that are independent of DCS data. Exercise increased the P(DCS) at P2. As a description of decompression "dose", the modified TR was superior to TR over a wider range of experimental conditions.

Efficacy of Doppler ultrasound [correction of utrasound] for screening symptoms of decompression sickness during simulated extravehicular activities

Doppler ultrasound is frequently used for monitoring circulating microbubbles during decompression to assess the symptoms of Decompression Sickness (DCS). This analysis was carried out to evaluate its effectiveness for screening symptoms of DCS during simulated extravehicular activities (EVA). The information from various hypobaric chamber studies carried out at the NASA Johnson Space Center, Houston, TX was used in this analysis (n=516). The circulating microbubbles were detected in the precordial area in 42% (218/516), and symptoms were reported in 16% (81/516) of these exposures. The accuracy of Doppler-detectable bubbles (Spencer grades) on all symptoms of DCS was examined by calculating measures of sensitivity and specificity. The efficacy of Doppler as a screening device was examined by calculating their positive predictive value (PPV) and negative predictive value (NPV). The results of these analyses indicated that the sensitivity of Doppler decreased, and the PPV increased with higher Spencer grades. However, the likelihood of detecting true negative cases (NPV) was consistently higher with all bubble grades. Due to the high false-positive rate and low prior probabilities of the risk of DCS, Doppler was found to be more useful to identify those who did not develop DCS, than to detect positive cases of DCS in the simulated EVA exposures.

Energy utilization rates during shuttle extravehicular activities

The work rates or energy utilization rates during EVA are major factors in sizing of life support systems. These rates also provide a measure of ease of EVA and its cost in crew fatigue. From the first Shuttle EVA on the STS-6 mission in 1983, we have conducted 59 man-EVA and 341 man-hours of EVA. Energy utilization rates have been measured on each of these EVA. Metabolic rate was measured during each EVA using oxygen utilization corrected for suit leakage. From 1981-1987, these data were available for average data over the EVA or over large segments of the EVA. Since 1987, EVA oxygen utilization data were available at 2-minute intervals. The average metabolic rate on Shuttle EVA (194 kcal/hr.) has been significantly lower than metabolic rates during Apollo and Skylab missions. Peak rates have been below design levels, infrequent, and of short duration. The data suggest that the energy cost of tasks may be inversely related to the degree of training for the task. The data provide insight on the safety margins provided by life support designs and on the energy cost of Station construction EVA.

Prostaglandin metabolism during growth and differentiation of the regenerating vertebrate appendage

House lizards are able to regenerate their tails. This is an ideal model to study the growth and differentiation of an organ. Prostaglandins (PGs) are local hormones having diverse and potent biological activities. In an effort to understand PG metabolism during the growth and differentiation of the regenerating lizard tail, we analysed the fatty acid (FA) composition of phospholipids are free FAs by GC, the activity of two rate-limiting enzymes (phospholipases A and C), the activity of the enzyme responsible for the oxygenation of polyunsaturated fatty acids to PGs (cyclooxygenase) and characterized the endogenous PGs by HPLC. It was observed that on the 20th day, i.e. the tissue differentiation period, there was an increase in phospholipase A activity, together with a sudden fall in the free arachidonic acid (AA) level, an increase in cyclooxygenase activity and the appearance of endogenous PGE2. PGE2 can stimulate cyclic adenosine monophosphate (cAMP) production and it may stimulate a cascade of events associated with tissue differentiation.

Patent foramen ovale and hypobaric decompression

Gas microbubbles were detected in the left ventricle of a supine subject being screened for an atrial septal defect as a participant of a hypobaric decompression study. This determination was made using the saline echocontrast procedure. We found provocation by a Valsalva maneuver not to be necessary in this individual for right-to-left passage of contrast microbubbles into the left heart and middle cerebral artery. When this same individual underwent hypobaric decompression to a simulated altitude of 21,000 ft, numerous gas microbubbles were detected in the right heart, but no gas bubbles were detected in either the left ventricular outflow tract or in the middle cerebral artery. This observation appears to be a novel finding, not previously reported.

Health of the elderly in a community in transition: a survey in Thiruvananthapuram City, Kerala, India

Results of a survey to assess the health and functional status of the elderly (defined as those who are 60 years or older) in Thiruvananthapuram city, the capital of Kerala state, India, are discussed. As the process of development results in longevity without concomitant economic success, traditional support systems break down. The differences in status of the elderly dependent on gender and socioeconomic class are highlighted. Women are poorer and generally suffer more morbidity than men in old age, even though their death rates are lower. The better-off among the elderly enjoy a quality of life much superior to their poor brethren. Thus, in transitional societies such as Kerala, socioeconomic status and gender play a significant role in determining the quality of life of the elderly, a finding which may have some policy implications.

Survivorship models for estimating the risk of decompression sickness

Several approaches have been used for modeling the incidence of decompression sickness (DCS) such as Hill's dose-response and logistic regression. Most of these methods do not include the time-to-onset information in the model. Survival analysis (failure time analysis) is appropriate when the time to onset of an event is of interest. The applicability of survival analysis for modeling the risk of DCS is illustrated by using data obtained from hypobaric chamber exposures simulating extravehicular activities (n = 426). Univariate analysis of incidence-free survival proportions were obtained for Doppler-detectable circulating microbubbles (CMB), symptoms of DCS and test aborts. A log-linear failure time regression model with 360-min half-time tissue ratio (TR) as covariate was constructed, and estimated probabilities for various TR values were calculated. Further regression analysis by including CMB status in this model showed significant improvement (p < 0.05) in the estimation of DCS over the previous model. Since DCS is dependent on the exposure pressure as well as the duration of exposure, we recommend the use of survival analysis for modeling the risk of DCS.

Early stopping of aerospace medical trials: application of sequential principles

A two-period, crossover trial was conducted in the hypobaric chamber on human subjects to compare the influence of inflight exercise (experimental) and restricted activity (control) on altitude decompression sickness (DCS) during simulated extravehicular activities. Out of 39 pairs (total of 78 exposures), 4 cases of DCS occurred under control and 5 occurred under experimental conditions. Analysis of the crossover results showed that the P values for differences in DCS occurrence was 0.56. Under these circumstances, it was necessary to decide whether additional information would be obtained by accruing more subjects. This problem was examined by using a skew sequential design in which the "stopping rule" was based on an alpha of 0.05 (one-sided) and power of 80%. The result of this analysis was in favor of the null hypothesis, and the trial was terminated. The authors recommend the use of similar stopping rules in aerospace trials to optimize sample size without compromising statistical validity.

Essential fatty acid metabolism in south Indians

Coronary artery disease (CAD), hypertension and diabetes mellitus are more common in Indians compared to their incidence in the Western population. The exact reason for this is not known. One of the risk factors for the development of and complications due to CAD, hypertension and diabetes mellitus could be hyperinsulinemia and insulin resistance and low plasma levels of arachidonic acid and eicosapentaenoic acid, metabolites of dietary essential fatty acids (EFAs), cis-linoleic and alpha-linolenic acids. Fatty acid analysis of the plasma phospholipid (PL) fraction of normal Indians showed that they have low concentrations of arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid in comparison to those seen in Canadian and Minnesota (USA) normals. Since insulin can activate EFA metabolism, this alteration in the EFA metabolism may, at least, in part explain the high incidence of CAD, hypertension and diabetes mellitus and insulin resistance and hyperinsulinemia that are common in Indians.

Epidemiology of decompression sickness under simulated space extravehicular activities

Several ground-based trials were conducted by NASA at the Lyndon B. Johnson Space Center, Houston, TX, during 1982-90 to examine the risk of altitude decompression sickness (DCS) during space extravehicular activities. There were 22 different pressure profiles involving single and staged decompression procedures, each lasting from 180 to 360 min at the final altitude. A total of 164 healthy subjects participated in 426 exposures to altitude. Symptoms of DCS occurred in 17% (74/426) and circulating microbubbles by precordial Doppler ultrasound were detected in 42% (179/426) of all exposures. About 27% (20/74) of exposures with symptoms resulted in test abort, and one-third of all test aborts required treatment in the hyperbaric chamber. There was about 3.20 times (95% Confidence Interval [95% CI] = 1.56-6.66) higher risk of symptoms in the presence of Doppler-detectable microbubbles. Examination of individual risk factors showed that there was about 4.3 times (95% CI = 1.62-11.50) higher risk of symptoms with increasing number of exposures. These findings emphasize the importance of evaluating risk factors from ground-based trials for application in operational decision-making and treatment strategies.

Oxy-radicals, lipid peroxides and essential fatty acids in patients with glomerular disorders

It is now believed that free radicals and eicosanoids participate in the pathogenesis of immune mediated mesangial cell injury and renal tissue damage including glomerulonephritis. But relatively little information is available about the role of essential fatty acids, (EFAs), the precursors of eicosanoids, in renal diseases. We studied the levels of superoxide anion, hydrogen peroxide, lipid peroxides and the concentrations of various metabolites of EFAs in the plasma phospholipid fraction of patients with glomerular disorders. A significant increase in the production of superoxide anion and hydrogen peroxide both by unstimulated and phorbol-myristate acetate (PMA)-stimulated leukocytes, increase in the plasma lipid peroxide levels and a marked reduction in the levels of arachidonic acid (AA) and eicosapentaenoic acid, the precursors of 2 and 3 series prostaglandins (PGs) respectively, were observed in these patients. Since eicosapentaenoic acid and prostacyclin, which is derived from AA, are believed to be of benefit in the prevention of progression of renal disease, and as free radicals can cause renal dysfunction, our results suggest that free radicals and the metabolites of EFAs play a significant role in the pathogenesis of glomerular disorders.

Are free radicals involved in the pathobiology of human essential hypertension?

Possible involvement of reactive oxygen species and nitric oxide in the pathogenesis of human essential hypertension was investigated. It was observed that both superoxide anion and hydrogen peroxide production by polymorphonuclear leukocytes and the plasma levels of lipid peroxides are higher in uncontrolled essential hypertension compared with normal controls. Nitric oxide levels measured as its stable metabolite nitrite, as an index of nitric oxide synthesis, revealed its levels to be low in hypertensive patients. Superoxide anion, hydrogen peroxide, lipid peroxides and nitric oxide levels reverted to normal values after the control of hypertension by drugs. The concentrations of anti-oxidants such as vitamin E and superoxide dismutase were found to be decreased in patients with uncontrolled hypertension. Several anti-hypertensive drugs inhibited lipid peroxidation in vitro. Angiotensin-II, a potent vasoconstrictor, stimulated free radical generation in normal leukocytes which could be blocked by calmodulin antagonists. These results suggest that an increase in free radical generation and a simultaneous decrease in the production of nitric oxide and anti-oxidants such as SOD and vitamin E occurs in essential hypertension. This increase in free radical generation can inactivate prostacyclin and nitric oxide and decrease their half life which can lead to an increase in peripheral vascular resistance and hypertension.

Time to detection of circulating microbubbles as a risk factor for symptoms of altitude decompression sickness

This study investigated the association between time at onset of circulating microbubbles (CMB) and symptoms of altitude decompression sickness (DCS), using Cox proportional hazard regression models. The study population consisted of 125 individuals who participated in direct ascent, simulated extravehicular activities profiles. Using individual CMB status as a time-dependent variable, we found that the hazard for symptoms increased significantly (at the end of 180 min at altitude) in the presence of CMB (Hazard Ratio = 29.59; 95% confidence interval [95% CI] = 7.66-114.27), compared to no CMB. Further examination was conducted on the subgroup of individuals who developed microbubbles during the test (n = 49), by using Cox regression. Individuals with late onset of CMB (> 60 min at altitude) showed a significantly reduced risk of symptoms (hazard ratio = 0.92; 95% CI = 0.89-0.95), compared to those with early onset (< or = 60 min), while controlling for other risk factors. We conclude that time to detection of circulating microbubbles is an independent determinant of symptoms of DCS.

Reactive oxygen species, lipid peroxides and essential fatty acids in patients with rheumatoid arthritis and systemic lupus erythematosus

We studied free radical generation, lipid peroxidation and the levels of essential fatty acids and of their metabolites in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Both superoxide and hydrogen peroxide generation by peripheral leukocytes but not malondialdehyde levels, as measured by thiobarbituric acid assay, were found to be significantly enhanced both in RA and SLE. Fatty acid analysis of the plasma PL fraction revealed that both LA and ALA metabolites are significantly decreased in RA and SLE compared to controls. These results suggest that essential fatty acid metabolism is altered in RA and SLE.

Informed consent: a study of experiences and opinion of utilizers of health services from India

One hundred and forty-eight subjects drawn from urban and rural settings who had been hospitalized for any medical problem within the previous three years were interviewed using a semi structured interview schedule to understand their opinion and experiences of informed consent. Sixty medical officers providing primary care in both urban and rural areas were concurrently interviewed to gather their opinion. Results revealed that respondents were dissatisfied with the information they had received about the different aspects of their illness. Both the doctors and the patients felt the need for providing adequate information to utilizers of health services. The two groups identified certain constraints, like illiteracy, in obtaining informed consent. Doctors compared to patients more often thought that illiterates could not understand the information. Patients more often felt that information about nature of investigations and about prognosis need not be routinely revealed.

Free radical generation, lipid peroxidation and essential fatty acids in patients with septicemia

Infections due to gram-negative bacteria and other organisms can lead to septicemia and shock in some patients. Endotoxins, which cause these pathophysiological events, stimulate macrophages to elaborate tumor necrosis factor and other lymphokines. These lymphokines can augment free radical generation by polymorphonuclear leukocytes, macrophages and other cells, which may ultimately produce respiratory distress syndrome, multiorgan failure and irreversible shock seen in septicemia. This is supported by our results presented here that there is indeed an increase in free radical generation and lipid peroxidation in patients with septicemia. In addition, analysis of plasma lipid profile in these patients showed that gamma-linolenic, dihomogamma-linolenic and arachidonic acids of n-6 series and alpha-linolenic and eicosapentaenoic acids of the n-3 series are decreased in their plasma phospholipid fraction. These results suggest that free radicals, lipid peroxides, and alteration in essential fatty acid metabolism may have a role in the pathogenesis of septicemia.

Threshold altitude resulting in decompression sickness

A review of case reports, hypobaric chamber training data, and experimental evidence indicated that the threshold for incidence of Altitude Decompression Sickness (DCS) was influenced by various factors such as prior denitrogenation, exercise or rest and period of exposure, in addition to individual susceptibility. Fitting these data with appropriate statistical models has the potential for estimating the frequency of occurrence of DCS at various altitudes under different experimental conditions and allows us to examine the influence of various factors on the threshold for DCS. This approach was illustrated by logistic regression analysis on the incidence of DCS below 9,144 m (30,000 ft). Estimations using these regressions showed that under a noprebreathe, 6-h exposure, simulated extravehicular activity profile, the threshold for symptoms occurred at approximately 3,353 m (11,000 ft); while under a no-prebreathe, 2-h exposure profile with knee-bends exercise, the threshold occurred at 7,925 m (26,000 ft). These examples showed that definition of threshold altitude should be qualified by the particular combination of experimental variables under which it was observed.