Fish muscle cytoskeleton integrity is not dependent on intact thin filaments.

Striated muscle cytoskeleton was studied by ultrastructure and electrophoresis. Treatment of sea bass white muscle myofibrils and glycerinated fibres with calpain caused disruption of costameres, intermediate filaments, and Z-line, without altering sarcomeres. V8 protease also caused loss of costameres and Z-line, and disrupted sarcomeres without affecting the intermediate filaments. Recombinant lipase caused loss of Z-lines and also sarcolemma detachment, without changing sarcomeres or intermediate filaments. DNase-1 removed thin filaments and partially removed Z-lines while leaving intact the sarcolemma attachments and intermediate filaments. Calpain, V8 protease, lipase and DNase-1 treatments induced extensive loss of alpha-actinin from the Z-line, which could be related to titin cleavage (calpain, V8), phosphoinositide hydrolysis (lipase), and actin depolymerisation (DNase-1). These results show that the cytoskeletal components are independent of intact thin filaments.

[Thrombosis from mechanical valve prostheses in the Reunion island]. / Thrombose de prothèses valvulaires mécaniques à l'île de la Réunion.

Between October 1991 and January 1995, 10 patients presented 14 episodes of thrombosis of mechanical valve prosthesis, 11 obstructive, 3 nonobstructive. In two cases, the thrombosis was recurrent (one after thrombolysis, one after surgical thrombectomy). In another two cases, the thrombosis was a recurrence (on a valve already surgically replaced because of thrombosis). Anticoagulant therapy had been ineffective in 9 cases; protein S deficiency was diagnosed in one case. Transoesophageal echography allowed diagnoses in all cases. Thrombolysis was the treatment of first intention in 9 cases (completed by a second course of thrombolysis in one case and by valvular replacement in two cases. The other patients were managed by immediate valve replacement in two cases, thrombectomy in one case, long-term parenteral anticoagulation in two cases (one of which was followed by valve replacement). Transoesophageal echography showed improved valve motion. Incomplete thrombus dissolution was observed in 50% of cases. Thrombolytic therapy was complicated by cerebrovascular accidents in two patients, one of which was fatal. One patient had regressive hemiplegia, one patient had a local hematoma. The authors conclude that thrombosis is a serious complication of valve replacement and usually occurs in patients inadequately anticoagulated. Thrombolysis may enable some patients to avoid reoperation but its risks limits its use to those patients thought to be unacceptable surgical risks. An apparently high frequency of this complication durind this period has led to the initiation of a study to determine the predisposing factors and to put preventive measures into action.

Production of influenza virus in cell cultures for vaccine preparation.

Influenza virus strains of different types for use as an inactivated vaccine have been successfully grown in different cell lines. Increasing titres were obtained with BHK-21/BRS, VERO and MDCK cells. Cultures in stationary flasks, in spinner cultures or in large bioreactor systems were tested and the optimal conditions were studied. MDCK cells grown in serum-free medium before and during the virus production phase were found to yield high titres in the presence of trypsin. Satisfactory results were obtained with egg-adapted strains of human and equine origin as well as with strains just isolated from human patients without any further passages in eggs or cell culture.

The transition from lay midwife to certified nurse-midwife in the United States.

This paper presents the results of a survey that was conducted between November 1992 and March 1993. Its target group consisted of midwives in the United States who began their careers as lay midwives and later decided to become certified nurse-midwives (CNMs). Questions address their demographic and socioeconomic characteristics to compile a profile that can be compared with other midwife populations. The survey elicited information regarding what motivated the decisions to change status and how these decisions have made an impact upon respondents' personal lives, family life styles, and income; identified how becoming a nurse-midwife changed the respondents' work in regard to their own community, the clientele they serve, and their style and site of practice, and how the change in identity affected their self-perceptions as midwives as well as their relationship to the health care system, the legal system, and the established midwifery system; it investigated how respondents viewed their preparation for midwifery and how they felt about the relationship of nursing to midwifery; and, it addressed how these midwives related to, were influenced by, and influenced the two major professional midwifery associations in the United States, the Midwives Alliance of North America and the American College of Nurse-Midwives. The results showed that, overall, the respondents valued their lay midwifery background, felt positive about their CNM educational programs, and showed a preference for direct entry and apprenticeship programs in which the RN is not a prerequisite.

[Traumatic tricuspid insufficiency. Apropos of 2 cases]. / Insuffisance tricuspide traumatique. A propos de 2 observations.

The authors report two cases of tricuspid regurgitation by a ruptured anterior papillary muscle secondary to non-penetrating thoracic trauma. In the presence of suggestive clinical and electrocardiographic abnormalities (systolic murmur, right heart failure, right bundle branch block), echocardiography confirmed the tricuspid regurgitation, showed its mechanism and excluded any other intracardiac lesions. Tricuspid annuloplasty was performed in both cases because of the persistence of failure or degradation of the patient's clinical condition. Peroperative echocardiography was used to judge the quality of the surgical repair in both cases. Traumatic tricuspid regurgitation is a rare condition and the diagnosis is often delayed. Echocardiography is the investigation of choice and guides treatment which is essentially valvular repair in symptomatic patients.

Sodium and angiotensin in hypertension induced by long-term nitric oxide blockade.

The influence of dietary sodium restriction and angiotensin II blockade on hypertension induced by a 25-day period of administration of the inhibitor of nitric oxide synthesis NG-nitro-L-arginine-methyl ester (10 mg/kg twice daily by gavage) was assessed in Wistar rats fed a normal or low sodium diet. In addition, the angiotensin II receptor blocker losartan (30 mg/kg once daily by gavage) was administered before and during NG-nitro-L-arginine-methyl ester in rats fed the normal sodium diet. At the end of the studies, conscious systolic arterial pressure increased similarly in NG-nitro-L-arginine-methyl ester-treated groups maintained on normal or low sodium intake. Moreover, a 25% reduction in cardiac output due to a decrease in stroke volume was observed in both groups. A slight but significant cardiac hypertrophic response was observed in hypertensive rats irrespective of sodium intake. At the completion of studies, plasma renin activity was similar to corresponding controls in the hypertensive groups on normal or low sodium intake. Losartan totally prevented the development of hypertension as well as the decrease in stroke volume and cardiac hypertrophy associated with NG-nitro-L-arginine-methyl ester treatment in rats on normal sodium intake. In conclusion, hypertension resulting from long-term blockade of nitric oxide synthesis was not affected by dietary sodium restriction. A crucial role for the renin-angiotensin system was demonstrated in this new model of hypertension.