Can a Single Muscle Fiber Model the Features of Myocardial Stunning?

The exact mechanisms that cause myocardial stunning are still unclear. We previously utilized a computer model of the ventricle that was effective in modeling the dominant observable features of stunning, but it was not simple to implement. This led to the design of a single muscle fiber model. The mathematical model of a muscle fiber consisted of three elements: a contractile element, a series elastic element, and a parallel elastic element. The model created length waveforms based on time-dependent force and contractile stiffness functions. This model was initially evaluated by entering the same regional parameter values used in the global dual region ventricular model. First a reduction of the contractile stiffness function was applied by reducing the peak stiffness by 30%, and then the rates of activation and deactivation were reduced by 20% while maintaining the peak values constant. The three-element model produced results very similar to the canine and ventricular model. Thus, it is concluded that the simpler three-element model provides an accurate model of the myocardial tissue and its deficiencies during stunning.     

Manifestation of depressive symptoms among adolescents. A comparison of Mexican Americans with the majority and other minority populations.

The purpose of this research was to investigate differential manifestation of depressive symptomatology among adolescents from diverse ethnocultural groups. Data from a national survey of persons 12 to 17 years of age (N = 2200) were analyzed, comparing responses of Anglo, African, Mexican, and other Hispanic Americans with a 12-item version of the Center for Epidemiologic Studies Depression Scale. The results indicated minimal differences in terms of item response and internal consistency-reliability among the four adolescent groups. However, there were differences in patterns of item endorsement, as indicated by principal component factor analysis. Anglo- and African Americans exhibited similar factor structure, represented by negative affect, positive affect, and psychosomatic symptoms. The two Hispanic groups also exhibited a three-dimensional pattern, but there was a tendency among Hispanic adolescents for somatic symptoms and negative affect symptoms to cluster together. This pattern may indicate a more prominent role of somatic complaints in the presentation of depression among Mexican Americans and other Hispanics.     

Reduction of scrotalized skin improves the cosmetic appearance of feminising genitoplasty

A modified labioplasty to improve the cosmetic appearance after feminizing genitoplasty is described. Good results were obtained in all five patients in whom the technique was utilized.     

Results of speech perception and speech production training for three prelingually deaf patients using a multiple-electrode cochlear implant.

Five studies were conducted to measure changes in the perception and production of selected speech targets, with training, in three prelingually deaf patients. The two adults and one adolescent were implanted with the Cochlear (Nucleus) multiple-electrode prosthesis. The studies were perception and production of nasal consonants; perception of syllable-final consonants; perception and production of alveolar consonants; auditory-visual perception of alveolar consonants; and perception and production of vowels. Perceptual data were collected in the audition (implant)-alone condition, except for the auditory-visual perception of alveolar consonants where the audition-alone, vision-alone, and auditory-visual conditions were used. Speech perception data in the audition-alone condition were also collected from four postlingually deaf adult implant patients, without training, to indicate differences between the two classes of patients. The three prelingually deaf patients generally showed some improvements in speech production. In perception, improvements were recorded only for individual patients in some studies. The performance of the adolescent was better than that of the two adults in all cases. The perceptual performance of the postlingually deaf patients was superior to that of the prelingually deaf patients in all cases.     

Pudendal Thigh Fasciocutaneous Flaps for Vaginal Reconstruction in Gynecologic Oncology

The pudendal thigh is a sensate fasciocutaneous flap supplied by the posterior labial artery. We report on the results of pudendal thigh flaps used for vaginal reconstruction in eight patients at the time of pelvic exenteration (6) and radical vaginectomy (2). Patients were interviewed and results were assessed 5 to 19 months after surgery. The flaps were raised in the thigh creases just lateral to the hair bearing area of the labia majora and included skin, subcutaneous tissues, deep fascia of the thigh, and the epimysium of the adductor muscles. Flap sizes varied from 9 × 4 cm to 15 × 6 cm. Bilateral flaps were used in seven patients. The flaps were technically easy to perform. Partial (apical) flap necrosis occurred in four patients. One patient developed complete necrosis of bilateral flaps, followed by an enterovaginal fistula. One patient whose flaps did not necrose developed a rectovaginal fistula at the site of rectal reanastomosis. The functional results are disappointing. The only patient having successful vaginal intercourse had a unilateral flap reconstruction following lower vaginectomy in a nonirradiated pelvis. No patient with bilateral flaps or prior pelvic irradiation has had successful coitus. Other long-term sequelae include vulvar pain (2), chronic vaginal discharge (2), hair growth (4), and protrusion of the flaps (2). These vulvovaginal symptoms discourage patients and their partners from genital contact. Breaching the integrity of the vulva to construct a neovagina that is likely to be unsuitable for sexual intercourse may deprive women of their only potential for normal genital sexual responsiveness. Techniques of vaginoplasty require continued assessment.     

An outbreak of Salmonella dublin infection in England and Wales associated with a soft unpasteurized cows' milk cheese.

An outbreak of Salmonella dublin infection occurred in England and Wales in October to December 1989. Forty-two people were affected, mainly adults, and most lived in south-east England. Microbiological and epidemiological investigations implicated an imported Irish soft unpasteurized cows' milk cheese as the vehicle of infection. A case-control study showed a statistically significant association between infection and consumption of the suspect cheese (p = 0.001). Salmonella dublin was subsequently isolated from cheeses obtained from the manufacturer's premises. Initial control measures included the withdrawal of the cheese from retail sale and a Food Hazard Warning to Environmental Health Departments, as well as a press release, from the Department of Health. Subsequently, a decision was taken by the manufacturer to pasteurize milk used in the production of cheese for the UK market and importation of the cheese resumed in June 1990.     

Blood flow of the areola and breast skin flaps during reduction mammaplasty as measured by laser Doppler flowmetry.

Blood flow changes during reduction mammaplasty were studied using laser Doppler flowmetry. Twenty-one patients (39 breasts) were entered into the study. Eight patients underwent a modified Skoog mammaplasty, 6 a central glandular pedicle mammaplasty, 2 an inferior pyramidal dermal flap mammaplasty, and 5 a glandular resection with free nipple grafts. Laser Doppler flowmetry was performed preoperatively, immediately postoperatively, 24 hours postoperatively, 48 hours postoperatively, and 2 weeks postoperatively. Laser Doppler flowmetry values (in milliliters per minute per 100 grams) measured at the areola declined by 23% (Skoog), 18% (central pedicle), and 21% (inferior pyramidal), in the immediate postoperative period. Values at 48 hours were 31% below baseline (Skoog), 14% below baseline (central pedicle), and 60% below baseline (inferior pyramidal). Values at 2 weeks postoperatively were 12% below baseline (Skoog), 2% above baseline (central pedicle), and 44% below baseline (inferior pyramidal). The free nipple grafts showed an 89% rise above baseline at 2 weeks. One patient's procedure was changed to a free nipple graft after a 92% Doppler flow reduction during a Skoog mammaplasty. The free nipple graft had the greatest blood flow. The central pedicle mammaplasty showed the least decline in areolar flow. The inferior pyramidal mammaplasty showed the greatest decline. Laser Doppler flowmetry is a clinically useful tool for monitoring intraoperative and postoperative nipple/areolar blood flow.     

Release of proinsulin from the human fetal beta cell.

beta cells in the human fetal pancreas are immature in that they release little or no insulin in response to nutrients, such as glucose. The aim of this study was to examine further the immaturity of these cells, specifically regarding the storage and release of the precursor of insulin, proinsulin. Explants of human fetal pancreas were cultured in vitro for 3 weeks. Levels of proinsulin remained relatively constant throughout at 0.04 +/- 0.002 (S.E.M.) pmol/mg per day with a molar ratio of proinsulin to insulin of 2.2 +/- 0.11%. This low ratio was slightly greater than that observed in culture medium conditioned by adult human islets (0.3 +/- 0.1%), but similar to that found in acid-ethanol extracts of cultured explants (1.4 +/- 0.3%). Passaging of human fetal pancreas for 3 months in diabetic nude mice, which should have caused some maturation of the fetal beta cell, did not change the proportion of proinsulin present. Culture of explants in the presence of 12-O-tetra-decanoylphorbol-13-acetate resulted in some inhibition of proinsulin release, but much less than that for insulin, so that the molar ratio increased to 15.4 +/- 1.6% from the control 3.5 +/- 0.3%. Static stimulation of cultured explants with 10 mmol Ca2+/l, 10 mmol theophylline/l, and these two agents together caused 15-, 4- and 10-fold enhancement respectively of proinsulin release; glucose, leucine, arginine and KCl had no effect. In contrast, all these agents caused significant insulin release, the last four to a much smaller extent (less than or equal to three fold) than the first three (10-, 19- and 65-fold respectively).(ABSTRACT TRUNCATED AT 250 WORDS)     

Clinical problem-solving using video simulation: an investigation

This paper examines the use of videotape simulation as a research method for the exploration of clinical problem-solving, the challenges posed and the strategies employed to overcome the difficulties encountered are discussed. The simulation forms part of a larger comparative study of outcomes of pre-registration nurse education programmes, commissioned by the English National Board for Nursing, Midwifery and Health Visiting.