Issues on human acceleration tolerance after long-duration space flights

This report reviewed the literature on human tolerance to acceleration at 1 G and changes in tolerance after exposure to hypogravic fields. It was found that human tolerance decreased after exposure to hypokinetic and hypogravic fields, but the magnitude of such reduction ranged from 0 to 30 percent for plateau G forces and 30 to 70 percent for time tolerance on sustained G forces. A logistic regression model of the probability of individuals with 25 percent reduction in +Gz tolerance after 1 to 41 days of hypogravic exposures was constructed. The estimated values from the model showed a good correlation with the observed data. A brief review of the need for in-flight centrifuge during long-duration missions was also presented. Review of the available data showed that the use of countermeasures (such as anti-G suits, periodic acceleration, and exercise) reduced the decrement in acceleration tolerance after long-duration space flights. Areas of further research include quantification of the effect of countermeasures on tolerance, and methods to augment tolerance during and after exposures to hypogravic fields. Such data are essential for planning long-duration human missions

A generalization of midzuno-sen sampling scheme for finite populations

This paper proposes a generalization of the classical Midzuno-Sen sampling procedure to allow more than one PPSWOR selection followed by SRSWOR draws. The Horvitz-Thompson (H-T) estimator, its variance and variance estimator are discussed. Two methods of controlling the sampling variability of the H-T estimator are outlined. These require simple transformations of the study or the auxiliary variates. They can also be viewed as attempts to make the sampling scheme IPPS. Simple numerical illustrations are given

The study of density variations in computed tomographic images of the liver and its clinical importance

The liver which is a common site of metastatic disease has prompted the researches to select it as the organ most often studied in the truncal body with recent advanced techniques. Computed tomography has become established as the imaging method of choice for routine screening of the liver. This study of density variations in computed tomographic images of the liver was done on sixty patients in the department of anatomy and the department of radiology, Stanley Medical College, Chennai. The study was done by two methods. 1. Non contrast study, 2. Contrast study. The fluctuations of the CT images of the liver were observed as • Focal decreased attenuation masses. • Hyper enhancing focal liver lesions on contrast enhanced computed tomography and • Generalized abnormal attenuation of the liver. The following disease entities with different density range was observed in this study. • Liver cyst - simple cyst. • Liver abscess. • Multiple abscesses. • Hydatid cyst. • Cirrhosis. • Hemangioendothelioma. • Hepatocellular carcinoma – solitary. • Multicentric hepatocellular carcinoma. • Secondaries liver – Hypodense. • Hyperdense secondaries liver. • Cholangiocarcinoma. • Normal anatomy.56 Seventeen cases were observed with normal anatomy of the liver. Diseases like hypodense secondaries, solitary hepatocellular carcinoma, liver abscess and cirrhosis of the liver were observed in majority of the patients. One rare case of hemangioendothelioma was observed in a six year old child, one case of cholangiocarcinoma was also observed. These observations of the density of the liver in CT is of much value to the surgeons in planning an accurate and conservative surgery. CT techniques to evaluate the liver have advanced during the past decade and continues to evolve. We now have a better definition of when and how to utilize these examination to review liver anatomy and disease processes for prompt diagnosis and treatment

Pre-operative ondansetron vs. metoclopramide for prevention of post-operative nausea and vomiting in elective lower-segment caesarean section under spinal anaesthesia

Background: The problem of nausea and vomiting is a very old but a less thought of problem. Nausea and vomiting are the most common distressing symptom in the postoperative period. Antiemetic drugs play an important role in therapy of post-operative nausea and vomiting (PONV). Though many drugs have been tried as prophylaxis and treatment of PONV, no drug has been proved significantly effective and hence, the present study was undertaken to compare the efficacy and safety of IV metoclopramide and IV Ondansetron as prophylaxis for postoperative nausea and vomiting in lower-segment caesarean section (LSCS) under spinal anaesthesia. Methods: After institutional approval and informed consent 100 ASA I & II patients undergoing non emergent LSCS taken for study. The patients were divided randomly into 2 groups of 50 each. Group I received IV metoclopramide 10mg and Group II received IV. Ondansetron 4mg. Anaesthetic management was standardized. The incidence of vomiting and retching as number of episodes was studied. Nausea was graded depending on the severity and data derived. Results: The mean age, weight and duration of surgery was not significantly different when compared group-1 parturiants with group-2. The mean episodes of emesis, nausea and retching at different postoperative duration were significantly decreased (p<0.05) in Ondansetron group when compared to metoclopramide group as postoperative time progresses. Conclusions: Injection ondansetron 4mg provided decrease in the incidence of PONV than metoclopramide as the side effects with these drugs were minimal.

Targeted Deletion of Neuropeptide Y (NPY) Modulates Experimental Colitis

Neurogenic inflammation plays a major role in the pathogenesis of inflammatory bowel disease (IBD). We examined the role of neuropeptide Y (NPY) and neuronal nitric oxide synthase (nNOS) in modulating colitis.Colitis was induced by administration of dextran sodium sulphate (3% DSS) or streptomycin pre-treated Salmonella typhimurium (S.T.) in wild type (WT) and NPY (NPY(-/-)) knockout mice. Colitis was assessed by clinical score, histological score and myeloperoxidase activity. NPY and nNOS expression was assessed by immunostaining. Oxidative stress was assessed by measuring catalase activity, glutathione and nitrite levels. Colonic motility was assessed by isometric muscle recording in WT and DSS-treated mice.DSS/S.T. induced an increase in enteric neuronal NPY and nNOS expression in WT mice. WT mice were more susceptible to inflammation compared to NPY(-/-) as indicated by higher clinical & histological scores, and myeloperoxidase (MPO) activity (p<0.01). DSS-WT mice had increased nitrite, decreased glutathione (GSH) levels and increased catalase activity indicating more oxidative stress. The lower histological scores, MPO and chemokine KC in S.T.-treated nNOS(-/-) and NPY(-/-)/nNOS(-/-) mice supported the finding that loss of NPY-induced nNOS attenuated inflammation. The inflammation resulted in chronic impairment of colonic motility in DSS-WT mice. NPY -treated rat enteric neurons in vitro exhibited increased nitrite and TNF-alpha production.NPY mediated increase in nNOS is a determinant of oxidative stress and subsequent inflammation. Our study highlights the role of neuronal NPY and nNOS as mediators of inflammatory processes in IBD

Does the gender of the subject affect perceived smile aesthetics when varying the dimensions of maxillary lateral incisors?

Objective To assess whether subject gender influences aesthetic opinion when altering the width of maxillary lateral incisors. Method Photographs of a male and a female smile, displaying only the lips and teeth, were digitally altered to produce images where the maxillary lateral incisor was proportioned 52%, 57%, 62%, 67%, 72% and 77% in relation to the width of the maxillary central incisor. The image was then made symmetrical. One hundred participants (50 male and 50 female) were asked to rank each set of photographs from 'most' to 'least attractive'. Result The 57% lateral incisor was considered the 'most attractive' with the 77% lateral incisor the 'least attractive' however no statistically significant difference existed with relation to subject or rater gender. Conclusion Neither the 'golden proportion' nor the 'Recurrent Aesthetic Dental' ('RED') proportion was deemed the most attractive. As subject gender did not have a significant effect, dentists should work to create aesthetic results on an individual basis, operating within a so-called 'golden range'