The external anal sphincter operates at short sarcomere length in humans

Background The length at which a muscle/sarcomere operates in vivo (operational length) and the length at which it generates maximal stress (optimal length) can be quite different. In a previous study, we found that the rabbit external anal sphincter (EAS) operates on the ascending limb of the length–tension curve, in other words at lengths shorter than its optimal length (short sarcomere length). In this study, we tested whether the human EAS muscle also operates at a short sarcomere length. Methods The length–tension relationship of the EAS muscle was studied in vivo in 10 healthy nullipara women. EAS muscle length was altered by anal distension using custom‐designed probes of 5, 10, 15, and 20 mm diameter. Probes were equipped with a sleeve sensor to measure anal canal pressure. The EAS muscle electromyograph (EMG) was recorded using wire electrodes. Ultrasound images of anal canal were obtained to measure EAS muscle thickness and anal canal diameter. EAS muscle stress was calculated from the anal canal pressure, inner radius, and thickness of the EAS muscle. Key Results Rest and squeeze stress of the anal canal increased with the increase in probe size. Similarly, the change in anal canal stress, i.e. the difference between the rest and the squeeze, which represents the active contribution of EAS to the anal canal stress, increased with the increase in probe size. However, increase in probe size was not associated with an increase in the external anal sphincter EMG activity. Conclusions & Inferences Increase in EAS muscle stress with the increase in probe size, in the presence of constant EMG (neural input), demonstrates that the human EAS muscle operates on the ascending limb of the length–tension curve or at low sarcomere lengths. We propose that surgically adjusting EAS sarcomere length may represent a novel strategy to treat fecal incontinence in humans.     

Impact of interpreters' approach on Latinas' use of amniocentesis.

Communication difficulties in multicultural clinical settings can be exacerbated by translators, but their actual impact on medical decisions has not been systematically evaluated. This study sought to determine the influence of translators participating in clinical encounters in which English-speaking clinicians offered amniocentesis to Spanish-speaking women by conducting systematic observations of 61 prenatal genetic consultations and recording translators' training and background characteristics and patients' amniocentesis decisions. Translators' behavioral styles were classified according to 10 inductively determined criteria. Translators' approaches were classified as Distant, Authoritative, or Missionary. Whereas the first category remained emotionally detached, the others sought to build rapport and trust with the patient. Quantitative analysis revealed statistically significant associations between translation styles that sought to engender trust and likelihood the pregnant woman agreed to amniocentesis. The authors conclude that translators' affective approaches can influence whether patients accept or decline amniocentesis.     

Kappa Delta Award paper. Tissue fluid pressures: from basic research tools to clinical applications

The two basic research tools developed to measure tissue fluid pressure (wick catheter) and osmotic pressure (colloid osmometer) have undergone extensive validation and refinement over the past 20 years. Using these techniques, basic science investigations were undertaken of edema in Amazon reptiles, pressure-volume relations in animals and plants, adaptive physiology of Antarctic penguins and fishes, edema in spawning salmon, tissue fluid balance in humans under normal conditions and during simulated weightlessness, and orthostatic adaptation in a mammal with high and variable blood pressures--the giraffe. Following and sometimes paralleling this basic research have been several clinical applications related to use of our colloid osmometer and wick technique. Applications of the osmometer have included insights into (a) reduced osmotic pressure of sickle-cell hemoglobin with deoxygenation and (b) reduced swelling pressure of human nucleus pulposus with hydration or certain enzymes. Clinical uses of the wick technique have included (a) improvement of diagnosis and treatment of acute and chronic compartment syndromes, (b) elucidation of tissue pressure thresholds for neuromuscular dysfunction, and (c) development of a better tourniquet design for orthopaedics. This article demonstrates that basic research tools open up areas of basic, applied, and clinical research.     

Prognostic significance of nuclear deoxyribonucleic acid ploidy patterns in resected hepatic metastases from colorectal carcinoma

Nuclear deoxyribonucleic acid (DNA) ploidy studies of paraffin-embedded archival tumor specimen blocks were performed by flow cytometry on extracted nuclei from 101 surgically resected hepatic metastases from colorectal cancer. In 28 patients, the corresponding primary carcinoma of the metastases was also studied. Tumor clinicopathology and clinical course of the patients were reviewed. Preparation of paraffin-embedded tissue specimens was performed by the technique of Hedley et al. and stained with propidium iodide according to the method of Vindelov et al. Eighty-eight of 101 metastatic tumors and 26 of 28 primary tumors yielded evaluable DNA histograms. Twenty-six metastases showed a DNA diploid pattern, 25 showed a significantly increased 4C peak (DNA tetraploid/polyploid), and 37 had a DNA aneuploid peak. Ploidy pattern was constant between primary and metastases in 84.6% of tumors. No significant relationship between host and tumor characteristics and ploidy pattern was found except for a correlation between grade 3 metastases and DNA aneuploid. Survival of patients with DNA aneuploid metastases was significantly less than that of patients with DNA diploid metastases (p = 0.03). However, among DNA nondiploid metastases, survival was significantly less for low DNA index metastases (less than or equal to 1.5) than for high DNA index (greater than 1.5) metastases (p less than 0.05). Flow cytometric DNA ploidy measurements may have prognostic value for patients with resected hepatic metastases from colorectal carcinoma.     

Trends in prostatectomy for benign prostatic hyperplasia among black and white men in the United States: 1980 to 1994

Objectives. To estimate the annual rate of discharge for prostatectomy for benign prostatic hyperplasia (BPH) in black and white men from 1980 to 1994 using the National Hospital Discharge Survey.Methods. Overall and race-, age-, and year-specific utilization rates were estimated for the civilian population in the United States. Length of stay was calculated for each discharge, and the results were plotted over time. An expected number of discharges based on the rates observed in 1980 was estimated to determine the impact of decreased prostatectomy rates on the number of procedures that would have been expected in this aging population.Results. Discharge rates for whites were within a narrow range (233.2 to 274.5 per 100,000) from 1980 through 1990 and then displayed a monotonic decline after 1991 to 131.3 per 100,000 in 1994. Rates for blacks were 10% to 24% lower from 1980 to 1991; the decline in discharge rates began in 1993 for blacks, and by 1994 the racial gap had closed. Length of stay decreased throughout the period but length of stay averaged 30% longer for blacks throughout. On the basis of the observed rates of 1980, there were more than 140,000 fewer prostatectomies performed for BPH in 1994 than would have been expected owing to the aging of the population.Conclusions. These data demonstrate that the black/white differences in prostatectomy for BPH that were observed in the 1980s have disappeared in recent years. Furthermore, rates have declined dramatically in all age- and race-specific groups. Further work is needed to determine whether this convergence in discharge rates is due to equalization of access to medical care or to differences in utilization of alternative therapies.     

Eccentric exercise‐induced injuries to contractile and cytoskeletal muscle fibre components

Exercise involving lengthening of an activated muscle can cause injury. Recent reports documented the mechanics of exercise‐induced muscle injury as well as physiological and cellular events and manifestations of injury. Loss of the cytoskeletal protein desmin and loss of cellular integrity as evidenced by sarcolemmal damage occur early during heavy eccentric exercise. These studies indicate that the earliest events in muscle injury are mechanical in nature, while later events indicate that it may be more appropriate to conclude that intense exercise initiates a muscle remodeling process. We conclude that muscle injury after eccentric exercise is differently severe in muscles with different architecture, is fibre type‐specific, primarily because of fibre strain in the acute phase, and is exacerbated by inflammation after the initial injury.