The effect of dialysate on peritoneal phagocyte oxidative metabolism

The respiratory and oxidative responses of human peritoneal polymorphonuclear leukocytes (PMN) and peritoneal macrophages (PM phi) following exposure to unused continuous ambulatory peritoneal dialysis fluid (CAPD) and early dwell effluent were studied using an open oxygen (O2) electrode system and by measurement of oxygen radical-derived luminol-dependent chemiluminescence. Both cell types responded to stimulation by increasing O2 consumption and by generating chemiluminescence even at external O2 concentrations below 50 microM O2. Oxygen concentrations in the dialysate, as measured by blood gas analysis, were never lower than 118 +/- 8.3 microM O2 even during active peritonitis. Thus oxygen availability does not appear to be rate limiting for phagocyte oxidative metabolism in the peritoneal cavity. Preexposure of both inflammatory cell types to unused fluid or early dwell CAPD effluent significantly reduced both stimulated oxygen uptake and the subsequent ability of these cells to generate chemiluminescence without significantly affecting their viability. Further investigation of this down regulatory phenomenon using unused fluid and laboratory prepared dialysis fluid revealed that low pH (5.3) and high sodium lactate concentration in combination are directly responsible for the suppressive effect of unused fluid and early dwell effluent on cell function. These observations demonstrate that cellular host defense may be impaired early in the dialysis cycle as a result of lactate mediated "stunning" of resident phagocytes. The precise nature of the molecular species responsible for this suppressive effect remains to be identified.     

Fixed prosthodontics in the elderly population. Life expectancy of fixed restorations, failures, and retreatment methods.

The restorative needs of older dental patients challenge the ingenuity, anatomic knowledge, artistic skills, occlusal philosophies, and material knowledge of the clinician. Achieving the most secure foundation while simultaneously eliminating imperfections and incorporating a design that promotes good oral hygiene and a natural and attractive appearance are significant contributors to a patient's welfare. The treatment decision regarding fixed prosthodontics for elderly patients requires the balancing of two opposing arguments: 1. In patients who are older, and who are perhaps medically or physically compromised, and, in addition, who may be on a limited budget (or perceived limited budget), it is important to fabricate dental prostheses that are as good as possible to minimize the likelihood that the prosthesis will need to be remade in the future when the patient is likely to be even more compromised financially, medically, or physically, and also to minimize the stress on the patient of accommodating to something that is less than an optimal dental solution. 2. Patients in this age group often anticipate financial strain in the future, perhaps realistically in view of the increasing percent of older adults who are institutionalized (5% of persons 65 years old or older, 20% of persons 80 years old or older). Also, many are reluctant to invest large amounts of money in their teeth when they are already quite elderly and realize they may not live long enough to make the investment "worthwhile." Educating the patient regarding average life expectancy is sometimes helpful, but the experience of many clinical dentists is that many elderly persons either do not believe the numbers, require greater certainty in their "investments," or do not place as high a value on their dental health as they do other aspects of their lives (in a context in which there are more needs than resources to pay for them). Finally, many older adults, contrary to the popular bumper sticker, are trying to preserve as many resources for their children and grandchildren as possible. The final decision should be made with sensitivity to the overall needs of the patient, and with the assistance of a well-informed patient or other responsible party.     

Evidence for persistence of adenovirus in the tear film a decade following conjunctivitis

Chronic papillary conjunctivitis has been described following adenoviral conjunctivitis. It is unknown however, how long adenovirus is able to persist in the tear film and conjunctiva. To determine if adenovirus persists in the ocular surface following adenoviral conjunctivitis, 304 patients with a history of adenovirus conjunctivitis from whom an adenovirus had been isolated 10 years previously were sent a questionnaire regarding persistent or recurrent symptoms and were invited to attend. Patients were examined and samples of tears and conjunctival cells were collected from both eyes using tear film washes, filter paper, and swabs, the latter for virus isolation. Extracted DNA from the ocular samples was amplified using primers for herpes simplex virus (thymidine kinase) and adenovirus (hexon) genes. Adenovirus amplicons were sequenced and compared to original serotype. Thirty patients attended, 19 of whom had persistent papillary conjunctivitis. Evidence of adenovirus DNA was detected in 17 of 30 patients, 15 of whom also had evidence of a chronic papillary conjunctivitis. Adenovirus DNA was significantly associated with papillary conjunctivitis (P = 0.03). Adenovirus amplicons were successfully sequenced from six patients. Four patients harbored type 3 adenovirus, the same serotype with which they were infected originally 10 years previously. Two patients were infected originally with adenovirus serotype 3 but the current serotype was type 4. Infection of the ocular surface with adenovirus may predispose to the development of a persistent or recurrent conjunctivitis, the presence of which, appears to be associated with evidence of long term persistence of adenovirus DNA.     

Long term health and neurodevelopment in children exposed to antiepileptic drugs before birth

Objective: To investigate the frequency of neonatal and later childhood morbidity in children exposed to antiepileptic drugs in utero.

Design: Retrospective population based study.

Setting: Population of the Grampian region of Scotland.

Participants: Mothers taking antiepileptic drugs in pregnancy between 1976 and 2000 were ascertained from hospital obstetric records and 149 (58% of those eligible) took part. They had 293 children whose health and neurodevelopment were assessed.

Main outcome measures: Frequencies of neonatal withdrawal, congenital malformations, childhood onset medical problems, developmental delay, and behaviour disorders.

Results: Neonatal withdrawal was seen in 20% of those exposed to antiepileptic drugs. Congenital malformations occurred in 14% of exposed pregnancies, compared with 5% of non-exposed sibs, and developmental delay in 24% of exposed children, compared with 11% of non-exposed sibs. After excluding cases with a family history of developmental delay, 19% of exposed children and 3% of non-exposed sibs had developmental delay, 31% of exposed children had either major malformations or developmental delay, 52% of exposed children had facial dysmorphism compared with 25% of those not exposed, 31% of exposed children had childhood medical problems (13% of non-exposed sibs), and 20% had behaviour disorders (5% of non-exposed).

Conclusion: Prenatal antiepileptic drug exposure in the setting of maternal epilepsy is associated with developmental delay and later childhood morbidity in addition to congenital malformation.

     

A simple and inexpensive metabolic cage for mice

An inexpensive and easily constructed metabolic cage for mice is presented. This apparatus can reliably monitor food and fluid consumption, as well as urine and fecal output, in a relatively non-intrusive manner.     

Pancreastatin secretion by pituitary adenomas and regulation of chromogranin B mRNA expression.

Pancreastatin, a carboxyl-terminal amidated peptide derived from chromogranin (Cg)A, inhibits secretion of insulin and parathyroid hormone. Our recent studies found significant amounts of immunoreactive pancreastatin in all pituitary adenomas except prolactin adenomas. To analyze the effects of pancreastatin on pituitary cell function, 17 cultured pituitary adenomas were examined for immunoreactive pancreastatin and pancreastatin secretion by the tumors. The effects of pancreastatin on pituitary hormone secretion and on pituitary hormone (follicle-stimulating hormone and prolactin), CgA, and CgB mRNA levels were also examined. Immunoreactive pancreastatin and CgA were present diffusely in gonadotroph and null cell adenomas, but only a few prolactin adenoma cells expressed pancreastatin or CgA. When cells were treated with hypothalamic peptides, gonadotroph adenomas were the only group that released increased amounts of pancreastatin in response to gonadotropin-releasing hormone (10(-7) mol/L). Pancreastatin (10(-7) mol/L) treatment did not stimulate pituitary hormone secretion significantly. In situ hybridization analyses showed that gonadotropin-releasing hormone and pancreastatin treatment led to significant increases in CgB and follicle-stimulating hormone mRNAs in gonadotroph adenomas, whereas CgA mRNA levels did not change significantly. These results show that there is a differential distribution of pancreastatin secretion in pituitary adenomas and that the hypothalamic hormone gonadotropin-releasing hormone and the CgA-derived peptide pancreastatin can regulate CgB mRNA in gonadotroph adenomas, suggesting an autocrine effect of pancreastatin on pituitary tumor function.     

The mechanical efficiency of treadmill running against a horizontal impeding force

1. A method for determining the apparent mechanical efficiency of running against a horizontal impeding force is described. The results of studies on three well trained athletes have been summarized.2. A linear relation was found between metabolic rate and external work rate. The apparent mechanical efficiency was calculated as the inverse of the slope of the linear regression line of metabolic rate on external work rate x 10(2) (percentage).3. The over-all mean for apparent load-running efficiency (LRE) was 36.1%. The differences in LRE between subjects were not statistically significant. No measurable change in LRE occurred with habituation.4. Values are given for E(k), the net energy cost of unloaded horizontal treadmill running per kilogram of bodyweight and per kilometre of distance covered. The over-all mean for E(k) was 0.83 kcal. kg(-1). km(-1).5. The efficiency values obtained are discussed and compared with other values of running efficiency obtained by different methods, and with studies on isolated muscle.