Stress governs tissue phenotype at the femoral insertion of the rabbit MCL

The cells in the midsubstance portion of skeletal ligaments typically have elongated shapes, but where ligaments insert into bone the cells appear very rounded and the tissue phenotype is that of fibrocartilage. Between the midsubstance and the insertions there is a gradient in cell shape and tissue phenotype that has been hypothesized to reflect a gradient of mechanical stresses. To test this hypothesis, cell shapes (an index of tissue phenotype) were quantified in the central part of the femoral insertion of the rabbit medial collateral ligament by computer-assisted histomorphometry. Morphometric measurements were correlated with the mechanical stresses and strains in the central part of the insertion as predicted by finite element analysis. Throughout the ligament the direction of the predicted principal tensile stresses coincides with the direction of the collagen fibers which curve from the midsubstance to meet the femur at nearly right angles. Principal compressive stresses also occur within the ligament: the highest are localized near the bone; the lowest in the midsubstance. The areas with the roundest cells correspond to the areas with the highest principal compressive stresses in the model; the areas with the flattest cells correspond to the areas with the lowest compressive stresses in the model. A correlation between cell shape and mechanical stresses suggests that physiological loading of the MCL is important for the maintenance of tissue phenotype throughout this insertion. We theorize that the cells in ligament insertions adapt to the prevailing local mechanical environment.     

Carcino-embryonic antigen activity in urine of patients with bladder carcinoma. Clinical evaluation of carcino-embryonic antigen. II

This paper deals with the study of CEA levels in urine from healthy control subjects, of patients with bladder carcinoma or previous bladder carcinoma, and other groups of patients. In 53% of the patients with bladder carcinoma and without urinary infection, urinary CEA was increased. There were no false positive results. It is concluded that urinary CEA is a valuable aid in the detection of malignant tumour growth in the bladder. The results are compared with several tumour parameters, e.g. tumour size, stage of disease and histological parameters. Evidence is presented that CEA in infected urine is not produced by bacteria and that, like soluble vaginal excretory products, this substance has antigenic groupings in common with CEA from bladder tumours.     

Temporal integration of acoustic energy

Bone-conduction measurements are inaccurate and often troubled by masking problems. Determination of the temporal integration of acoustic energy by Brief Tone Audiometry permits an estimate of the cochlear threshold. In 71 patients with middle ear pathology, the conductive impairment was measured using both conventional audiometry and Brief Tone Audiometry. In 85% of the patients, the estimates coincided within 15 dB. Results from pre- and post-operative measurements are given, and it is demonstrated that Brief Tone Audiometry can be used as an alternative to bone-conduction audiometry to determine the degree of conductive loss with the same accuracy, but without the latter's limitations.     

A poly(A) binding protein functions in the chloroplast as a message-specific translation factor

High-affinity binding of a set of proteins with specificity for the 5' untranslated region (UTR) of the Chlamydomonas reinhardtii chloroplast psbA mRNA correlates with light-regulated translational activation of this message. We have isolated a cDNA encoding the main psbA RNA binding protein, RB47, and identified this protein as a member of the poly(A) binding protein family. Poly(A) binding proteins are a family of eukaryotic, cytoplasmic proteins thought to bind poly(A) tails of mRNAs and play a role in translational regulation. In vitro translation of RNA transcribed from the RB47 cDNA produces a precursor protein that is efficiently transported into the chloroplast and processed to the mature 47-kDa protein. RB47 expressed and purified from Escherichia coli binds to the psbA 5' UTR with similar specificity and affinity as RB47 isolated from C. reinhardtii chloroplasts. The identification of a normally cytoplasmic translation factor in the chloroplast suggests that the prokaryotic-like chloroplast translation machinery utilizes a eukaryotic-like initiation factor to regulate the translation of a key chloroplast mRNA. These data also suggest that poly(A) binding proteins may play a wider role in translation regulation than previously appreciated.     

The obstructive sleep apnoea syndrome--experience of a referral centre

OBJECTIVE: The aims of this study were: (i) to document the presence and severity of obstructive sleep apnoea (OSA) in patients who complained of heavy snoring and other symptoms suggestive of the OSA syndrome; (ii) to examine the correlation between the clinical and polygraphic findings, and (iii) to document the efficacy and compliance of nasal continuous positive airway pressure (CPAP) among these Asian snorers with OSA. METHODS: We analysed our clinical and nocturnal polysomnographic data between January 1986 and December 1995 for physician-referred patients who had complained of snoring and other symptoms suggestive of OSA. RESULTS: A total of 277 diagnostic studies were performed of which 145 (52%) were positive to OSA. For studies performed in the last 2 years (n = 125), 72 of the 125 were positive for OSA. Anthropometric data was not discriminative between the OSA positive snorers and the OSA negative snorers. We found that hypertension and choking were the most significantly related to OSA, conferring a 7 and 4 times relative risk respectively. Nasal CPAP eliminated snoring, apnoeas and oxygen desaturations completely in almost all cases and there were only minor mask-related side effects. CONCLUSION: OSA may not be uncommon among Asian snorers. Of the major traits for OSA risk among our local population, a history of hypertension and reports of nocturnal choking were the most significantly related. We have also shown that nasal CPAP is safe and effective among our local snorers and should be considered a first-line treatment for OSA.