Knee posture predicted from subchondral apparent density in the distal femur: an experimental validation.

Spatial patterning in the apparent density of subchondral bone can be used to discriminate between species that differ in their joint loading conditions. This study provides an experimental test of two hypotheses that relate aspects of subchondral apparent density patterns to joint loading conditions. First, the region of maximum subchondral apparent density (RMD) will correspond to differences in joint posture at the time of peak locomotor loads; and second, differences in maximum density between individuals will correspond to differences in exercise level. These hypotheses were tested using three age-matched samples of juvenile sheep. Two groups of five sheep were exercised, at moderate walking speeds, twice daily for 45 days on a treadmill with either a 0% or 15% grade. The remaining sheep were not exercised. Sheep walking on the inclined treadmill used more flexed knee postures than those in the level walking group at the time of peak vertical ground reaction forces. Kinematic measurements of knee posture were compared with knee postures estimated from the spatial position of the RMD on the medial femoral condyle. Our results show that the difference in the position of the RMD between the incline and level walking groups corresponded to the difference in knee postures obtained kinematically; however, exercised and nonexercised sheep did not differ in the magnitude of apparent density. These results suggest that patterns of subchondral apparent density are good indicators of the experimental modifications in joint posture during locomotion and may, therefore, be used to investigate differences between species in habitual joint loading.

Culture of the organism that causes rhinosporidiosis.

The causative agent of rhinosporidiosis is a microscopic round body in polypoidal masses that is believed to be the sporangium of a fungus Rhinosporidium seeberi. But fungal aetiology can not be proved with certainty. Attempts to culture the fungus on various media have also been unsuccessful. In a recent study pond water samples, from water in which patients had been bathing, were analysed and a unicellular prokaryotic cyanobacterium Microcystis aeruginosa was isolated. The same cyanobacterium was demonstrated in clinical samples from patients with rhinosporidiosis. Consequent to these findings, attempts were made to culture the causative organism of rhinosporidiosis under conditions that support growth of cyanobacteria. This study describes a simple method for laboratory culture of this organism. Observations based on laser-scanning confocal microscopy, light and electron microscopy confirm that a cyanobacterium, Microcystis sp. is the causative agent of the disease. Rhinosporidiosis is the first human disease to be shown to be caused by a cyanobacterium. The findings have opened the way for development of therapy.

An assessment of oral cancer prevention curricula in U.S. medical schools.

BACKGROUND: Oral cancer is readily detectable through routine examination, but five-year survival rates remain low. Physicians bear the same responsibilities as dentists in the early detection of oral cancers, because high-risk patients utilize medical services more often than dental services. METHODS: Because physicians' practices are largely influenced by their training, this study assessed the level of oral cancer education provided to undergraduate U.S. medical students. Health history and physical diagnosis course curricula were assessed for relevant content. RESULTS: The response rate from the U.S. medical schools was 63.2%. When compared with the "gold standard," the average score was 43% of the optimum. Seven percent of the schools did not require inspection of the mouth, 29% required inspection of all oral structures, and intraoral palpation was advocated by 43% of the schools. Although most schools included questions about alcohol and tobacco use, only 13% asked about sunlight exposure. CONCLUSION: Preliminary oral cancer training in medical schools regarding physical assessment and elicitation of signs, symptoms, and high-risk behaviors lacks both adequacy and comprehensiveness.

Rhinosporidiosis: a study that resolves etiologic controversies.

We have been able to isolate the cyanobacterium Microcystis aeruginosa from water samples of ponds and river where patients of rhinosporidiosis were bathing. It is likely that this cyanobacterium is the causative agents of this disease. The bluish-green cells of M. aeruginosa also have a colorless small cell stage called nanocyte which has been detected in clear waters of all the pond and river samples studied. Both large cells and nanocytes of M. aeruginosa could be recognized inside the round bodies of rhinosporidiosis by light and electron microscopy. Further work on culturing this organism from excised samples and evaluation for drug therapy are in progress. It is hoped that, if therapy becomes available, no surgery would be required for this disease. It is suggested that the waters from ponds and lakes, as well as municipal and recreational waters, be checked for the nanocyte stage of M. aeruginosa. Etiological controversies of rhinosporidiosis have been reasonably solved. The new findings justify a change in the name "rhinosporidiosis" that had been associated with the fungus Rhinosporidium Seeberi.

An epidemiological study of obesity in Shimla Town.

A cross sectional study of 888 randomly selected subjects in Shimla town was done to determine prevalence of obesity, its relation to age and physical activity. The prevalence of obesity was 21.5% using cut off levels of BMI 25. The prevalence of obesity rose significantly with age. Obesity was less in those having moderate physical activity as compared to those with low and high activity. Primary prevention is required to tackle this disease risk factor through health education focussing on promotion of moderate regular physical activity.

Accessing MEDLINE from the dental office.

Electronic access to on-line information is now available for dentists. One such resource is MEDLINE, a database of more than 7,500,000 biomedical references indexed by the National Library of Medicine. MEDLINE searching can be performed on-line or locally using a CD-ROM drive. Dentists should evaluate equipment requirements, availability of training, extent of the bibliographic database, ease of using the searching software and adequacy of documentation before selecting a mode of MEDLINE access.

New interpretations in rhinosporidiosis, enigmatic disease of the last nine decades.

Fungal etiology is widely quoted for the disease rhinosporidiosis. Identity of the fungal sporangium and its relationship with the disease have baffled medical scientists and mycologists for several decades. This study provides unequivocal evidence against involvement of fungus in rhinosporidiosis. The so-called sporangium is found to be a unique body containing residue-loaded lysosomal bodies ('spores') for elimination from the system. 'Sporangia' have been redesignated nodular bodies (NB) and 'spores' as spheres of cellular waste (scw). Two carbohydrates, namely defective proteoglycans synthesized intracellularly and an exogenous polysaccharide ingested through diet of tapioca constitute indigestible material in NB and scw. Polysaccharide in NB which has beta, 1-4 glycosidic bonds between mannose residues is not degraded by gastrointestinal enzymes nor in intracellular lysosomes which break only alpha-glycosidic bonds. A link between NB and dry tapioca has been deduced. Rhinosporidiosis is a complex phenotype with perhaps no parallel in medical science. This report erases 99 years (1892-1991) of controversies regarding 'causal organism' of rhinosporidiosis.

Identification of the primer binding domain in human immunodeficiency virus reverse transcriptase.

We have labeled the primer binding domain of HIV1-RT with 5'-32P-labeled (dT)15 primer using ultraviolet light energy. The specificity of the primer cross-linking to HIV1-RT was demonstrated by competition experiments. Both synthetic and natural primers, e.g., p(dA)15, p(dC)15, and tRNA(Lys), inhibit p(dT)15 binding and cross-linking to the enzyme. The observed binding and cross-linking of the primer to the enzyme were further shown to be functionally significant by the observation that tRNA(Lys) inhibits the polymerase activity on poly(rA).(dT)15 template-primer as well as the cross-linking of p(dT)15 to the enzyme to a similar extent. At an enzyme to p(dT)15 ratio of 1:3, about 15% of the enzyme can be cross-linked to the primer. To identify the domain cross-linked to (dT)15, tryptic peptides were generated and purified by a combination of HPLC on a C-18 reverse-phase column and DEAE-Sephadex chromatography. A single peptide cross-linked to p(dT)15 was identified. This peptide corresponded to amino acid residues 288-307 in the primary sequence of HIV1-RT as judged by amino acid composition and sequence analyses. Further, Leu(289)-Thr(290) and Leu(295)-Thr(296) of HIV1-RT appear to be the probable sites of cross-linking to the primer p(dT)15.

Rhinosporidiosis associated with squamous cell carcinoma in the tongue.

The peritumoural region of a squamous cell carcinoma of the tongue when examined with light and electron microscope showed nodular bodies in the submucosa with all the distinctive features of 'sporangium and 'spores' of rhinosporidiosis. The occurrence of rhinosporidiosis in the tongue along with malignancy has not been reported hitherto. Some interesting observations and causal relationships are discussed.

Aerobic and anaerobic respiration in the intact spinach chloroplast.

Aerobic and anaerobic chloroplastic respiration was monitored by measuring (14)CO(2) evolution from [(14)C]glucose in the darkened spinach (Spinacia oleracea) chloroplast and by estimating the conversion of fructose 1,6-bisphosphate to glycerate 3-phosphate in the darkened spinach chloroplast in air with O(2) or in N(2) with nitrite or oxaloacetate as electron acceptors. The pathway of (14)CO(2) evolution from labeled glucose in the absence and presence of the inhibitors iodoacetamide and glycolate 2-phosphate under air or N(2) were those expected from the oxidative pentose phosphate cycle and glycolysis. Of the electron acceptors, O(2) was the best (2.4 nanomoles CO(2) per milligram chlorophyll per hour), followed by nitrite and oxaloacetate. With respect to glycerate 3-phosphate formation from fructose 1,6-bisphosphate, methylene blue increased the aerobic rate from 3.7 to 5.4 micromoles per milligram chlorophyll per hour. A rate of 4.8 micromoles per milligram chlorophyll per hour was observed under N(2) with nitrite and oxaloacetate.

Inhibition of chloroplastic respiration by osmotic dehydration.

The respiratory capacity of isolated spinach (Spinacia oleracea L.) chloroplasts, measured as the rate of (14)CO(2) evolved from the oxidative pentose phosphate cycle in darkened chloroplasts exogenously supplied with [(14)C]glucose, was progressively diminished by escalating osmotic dehydration with betaine or sorbitol. Comparing the inhibitions of CO(2) evolution generated by osmotic dehydration in chloroplasts given C-1 and C-6 labeled glucose, 54% and 84% respectively, indicates that osmotic dehydration effects to a greater extent the recycling of the oxidative pentose phosphate intermediates, fructose-6P and glyceraldehyde-3P. Respiratory inhibition in the darkened chloroplast could be alleviated by addition of NH(4)Cl (a stromal alkylating agent), iodoacetamide) an inhibitor of glyceraldehyde-3P dehydrogenase), or glycolate-2P (an inhibitor of phosphofructokinase). It is concluded that the site which primarily mediates respiratory inhibition in the darkened chloroplast occurs at the fructose 1,6-bisphosphatase/phosphofructokinase junction.

Ultrastructural features that relate to tumor cell behaviour in human breast carcinomas.

Human breast tumor biopsies were studied by transmission electron microscopy for ultrastructural characteristics that might be associated with tumor cell function and behaviour. Features related to the state of cell differentiation and tumor cell detachment were evaluated and discussed. The ultrastructure of loose cells at the tumor periphery is compared with that of coherent cells in interior regions. Structural information has been analysed by taking into account available biochemical data for interpretation of cell function. The value of the parameters chosen for study is discussed. This study shows that each tumor needs to be evaluated independently for its specific ultrastructural features. Electron microscopic data becomes more relevant when interpreted in conjunction with histological diagnosis and clinical findings.

Chromosome aberrations and dominant lethals in Culex fatigans due to mercuric chloride.

The mosquito, Culex fatigans, was used for determining the possible mutagenic potential of mercuric chloride, using chromosome aberrations and frequency of dominant lethals as the parameters. As many as 27.75 +/- 0.85% aberrations against 2.75 +/- 0.35% (P less than 0.001) in the controls were observed in the chromosomes of the animals treated with 0.001 microgram/ml of mercuric chloride. Similarly the frequency of dominant lethals was statistically significant in the treated lot. The results indicate that this compound is genotoxic.

Comparative ultrastructure of cancerous and normal human breast cells: demonstration of cytoskeleton by TEM.

A technique for the study of the cytoskeleton by transmission electron microscopy is described. It preserves cytoplasmic and nuclear ultrastructural details as well as cytoskeletal elements enabling a correlated study. There are no significant differences in organization and distribution of intermediate filaments between cancerous and normal breast cells. Close association between cytokeratin filaments and cell structures has been established from stereotilted images. Cytokeratin filaments in contact with cell structures are in the form of bundles; in the free 'space' of cytoplasm meshworks are organized. The intermediate filament system could possibly be organized for participation in diverse functions in a cell.

Evaluation of certain tranquillisers and sedative premedications on the safety index of volatile anaesthetics.

Safety index (S.I.) of ether, chloroform and halothane was determined in mice following premedication with chloral hydrate, phenobarbitone, diazepam and trifluoperazine given alone or in combination with atropine or hyoscine. The S.I. of ether was significantly raised by chloral hydrate and phenobarbitone when combined with atropine while trifluoperazine in combination with atropine or hyoscine lowered it. The S.I. of chloroform and halothane was raised by chloral hydrate, phenobarbitone and diazepam. The S.I. raising effects were augmented in chloroform anaesthesia and reduced in cases of halothane (except diazepam-hyoscine) when these premedications were combined with atropine or hyoscine.