Effects of triiodothyronine and dexamethasone on plasma and tissue angiotensin converting enzyme in the rat

Summary— In order to identify tissue specific regulation of angiotensin converting enzyme (ACE), the effects of dexamethasone (0.04 mg sc per day for 7 days) and triiodothyronine (T3) (0.5 mg/kg sc per day for 10 days) on ACE activity were investigated in different tissues in male Wistar rats. ACE activity was measured by fluorimetry in the plasma, heart, lung and kidney. In the kidney, ACE activity was measured in the medulla, cortex and brush border of proximal tubular cells and ³H-ramiprilat binding was used to characterise the changes in brush border ACE activity. Dexamethasone elicited a significant increase in lung ACE activity and a significant decrease in plasma ACE activity, but did not alter enzyme activity in the other tissues studied. T3 produced a significant decrease in lung ACE activity and an increase in ACE activity in the plasma and heart. In the kidney, ACE activity was not modified in the medulla whereas in the cortex and brush border ACE activity was doubled. This increase in ACE activity corresponded to a similar increase in the maximum number of binding sites of ³H-ramiprilat, suggesting that the increase in activity corresponded to an increase in the ACE level. The increased heart and kidney ACE activity in response to T3 may contribute to the cardiovascular effects of thyroid hormones through increased local angiotensin II generation. These results show that under dexamethasone or T3, ACE activity can vary from one tissue to another, suggesting that the ACE regulatory mechanism acts differently in each tissue.     

How the medical comorbidity of depressed patients differs across health care settings: results from the Medical Outcomes Study

OBJECTIVE: Although depression is one of the most common problems of medical and psychiatric outpatients, it has not been clear whether the extent of medical comorbidity among depressed patients varies across major types of clinical settings in which depressed patients receive care--especially by type of treating clinician (general medical versus mental health specialty) or type of payment for services (prepaid versus fee-for-service). METHODS: The authors examined these issues using data on 1,152 adult outpatients with current depressive symptoms and a lifetime history of unipolar depressive disorder who received care in one of three health care delivery systems in three U.S. sites. RESULTS: Depressed patients had a similarly high prevalence (64.9%-71.0%) of any of eight common chronic medical conditions whether they were seen in the general medical or specialty mental health sector; however, those visiting medical clinicians had a significantly higher prevalence of the two most common chronic medical conditions, hypertension and arthritis. Among depressed patients with hypertension, those visiting the general medical sector were more likely to be taking antihypertensive medication than were those visiting the mental health specialty sector. Type of payment (prepaid versus fee-for-service) was unrelated to either prevalence or severity of comorbid medical conditions, suggesting that the typical depressed patient in all types of practices studied had medical comorbidity. CONCLUSIONS: These data suggest that clinicians in all health care settings must be prepared to encounter chronic medical conditions and complaints in the depressed patients who visit them.     

Central venous catheter infections in AIDS patients receiving daily home therapy for cytomegalovirus disease

We studied the infection rate of long-term intravenous access used for daily home treatment of cytomegalovirus (CMV) disease in 61 AIDS patients who had 75 central venous catheters implanted for antiviral maintenance therapy between February 1989 and December 1994. In 39 patients (64%) the risk factor for AIDS was intravenous drug abuse. Sixty-three catheters were Hickman type and 12 were totally implanted ports. The cumulative follow-up time was 19000 catheter-days (52 patient-years), with median duration of placement of 249 days. The infection rate was 0.22 infections per 100 catheter days. The probability of remaining free of catheter-related sepsis was 58% at 6 months. In 25 cases (61%) antimicrobial therapy without catheter removal was successful. Three patients died because of a catheter- related infection (mortality rate 7.3%). Infection-free survival time was not related to the risk factor for AIDS (p = 0.44) or type of device (p = 0.41). The total infection rate in these patients receiving daily home maintenance therapy for CMV disease through a long-term catheter was similar to that in other AIDS patients receiving weekly treatment in hospital facilities.      

Graft patency evaluation with DSA after reconstructive venous surgery

Evaluation of graft patency following reconstructive venous surgery may be difficult, especially in patients in whom a distal arteriovenous fistula has been constructed. We describe a method of visualizing these venous bypass grafts using digital subtraction angiography that is easy and provides satisfactory results.     

Skull radiography in infants: potential hazards of the use of head clamps

In six infants, aged 2 days to 3 months, the use of head clamps for immobilization during radiography resulted in depression of the cranial vault. In all of the infants the depression disappeared after removal or repositioning of the clamp. However, because of the possible unfavorable consequences, head clamps with spongy, larger surface areas should be used in infants.     

Effect of growth hormone treatment on craniofacial growth in Turner's syndrome

A cephalometric study was performed in 19 patients with Turner's syndrome, aged 8.7–16.5 years. A lateral roentgencephalogram was taken before and after two years of treatment with biosynthetic growth hormone in a dose of 24 IU/m²/week. During two years of growth hormone treatment, the mandibular length increased mainly due to vertical growth. The initially posteriorly rotated mandible showed an anterior rotation, although the normal position was not reached. The other linear measurements and angles did not change during treatment. No indications were found for an increase in the disproportionate growth or for excessive chin growth as a sign of acromegaly during growth hormone treatment. In conclusion, growth hormone treatment in patients with Turner's syndrome resulted in an increase in mandibular length, mainly due to vertical growth of the ramus and in the anterior rotation of the mandible.     

B cell-dependent T cell development

T and B cells are thought to develop independently. While it is widely recognized that T cells help B cells in the production of antibodies to protein antigens, less well understood is whether or how B cells contribute to T cell development and function. Defects in cell-mediated immunity in individuals with B cell deficiency and in B cell-deficient mice suggest that B cells contribute to T cell function. The question of whether T cell development is B cell dependent was revisited using two novel mouse strains: mice with monoclonal T cells (MT) and mice with monoclonal compartments of both B and T cells (MBT). It was found that T cell development and thymocyte selection is modified by the presence of B cells. These results suggest that B cells, or B cell products, contribute to thymocyte selection and T cell development.