Critical appraisal and further development of the methodology for open circuit calorimetry in neonates.

A non-invasive technique for open circuit calorimetry based on a Vickers 79 incubator as the gas collection chamber was developed and evaluated. The technique, which involved drawing air from the incubator hood at 11 1/min for gas analysis, did not have a significant cooling effect on the infant and the noise levels within the incubator did not exceed current safety standards. A new technique for checking the calibration of the whole system was developed as the traditional alcohol burn method proved unsatisfactory. Either pure oxygen or carbon dioxide were fed into the incubator hood at controlled physiological rates using a calibrated throttling valve. Over a number of calibration checks the mean error of the system proved to be +/- 4.3% for oxygen and +/- 4.45% for carbon dioxide. Less than a fifth of this error was attributable to the pump and flow meter. When oxygen is introduced to the system at a constant physiological rate it takes 30 min for a plateau to be reached. Therefore it is recommended that this system is used when readings are to be taken in a steady state situation or data is to be cumulated over a long period of time such as in an energy balance study. A run in period of 30 min before collecting data is essential. It is recommended that a calibration check is performed before each study.     

A preliminary investigation into the long-term injury consequences reported by retired baseball players

Seventy-five retired baseball players participated in a survey (37.8% response rate) in order to establish the long-term consequences of injuries sustained during their playing careers. Respondents had a mean age of 55.8 (+/-11.4) years with a mean age of 41.3 (+/-11.4) years at retirement from play. The mean overall rate of injury suffered per player/playing career was 5.6 (+/-7.1). 54.7% of respondents experienced a major injury (i.e. injury resulting in 5 or more consecutive weeks absence from training and play) with a mean major injury per player/playing career of 1.5 (+/-2.2). The rate for significant injuries (i.e. injury resulting in more than 1 week but less than 5 weeks absence from training and play) was 4.1 (+/-6.5) per player/playing career. Catchers had significantly less injuries than all other positions (p=0.027). 18.7% of all respondents reported suffering from arthritis, 24% from restricted joint mobility and 4% from chronically stiff fingers; all of these conditions were associated with their participation in baseball based on medical examination by their GP or medical specialist. 29.3% of respondents indicated that they had incurred additional medical costs and 12% reported significant loss of income associated with their injuries. Some injuries were severe enough that they resulted in extended stays in hospital producing costs carried by the health care system.     

Long-term acceptance of continuous positive airway pressure in obstructive sleep apnea

We studied the long-term acceptability of nasal continuous positive airway pressure (CPAP) treatment in 168 consecutive patients, 147 with obstructive sleep apnea (OSA) and 21 with snoring. Follow-up was between 1.5 and 78 months. At latest follow-up 107 of 168 (64%) were still using CPAP. Acceptance of CPAP was least for patients with snoring alone (6 of 21 persisted) and best for patients with both excessive daytime somnolence and severe hypoxemia (minimum SaO2 less than 75%), of whom 40 of 45 (89%) persisted with treatment. Patients with excessive daytime somnolence but without severe hypoxemia were less tolerant of CPAP (39 of 71, 55%, persisted) than patients with no symptoms of excessive somnolence but with severe hypoxemia (21 of 30, 70%, persisted). The most common reasons for discontinuing CPAP were intolerance of the mask (26 of 61), the inconvenience of treatment (16 of 61), and the lack of symptomatic benefit from treatment (10 of 61). We concluded that long-term acceptance of CPAP was difficult to predict in advance but that it was most likely in patients with the most severe sleep apnea. Because intolerance of the mask and inconvenience were the most common reasons for ceasing treatment, improvements in the design of CPAP systems and careful patient training may improve the acceptability of CPAP substantially.     

A clinical trial of adjunctive oestrogen treatment in women with schizophrenia

Summary A double-blind, 28-day, placebo-controlled study was conducted with three groups of women of child-bearing age (N = 12 in each group) who received standardised antipsychotic medication plus a) 50 μg transdermal estradiol or b) 100 μg transdermal estradiol or c) transdermal placebo. Preliminary analyses show that women receiving 100 μg of estradiol made greater improvements in the symptoms of schizophrenia than either the 50 μg estradiol or placebo groups. The addition of 100 μg adjunctive transdermal oestrogen significantly enhanced treatment responsivity of acute, severe psychotic symptoms in women with schizophrenia. The positive impact of oestrogen treatment on psychotic symptoms via a multiplicity of possible actions (see accompanying articles in this issue) may prove clinically useful in the overall treatment of women with schizophrenia. Accepted June 2002, Published online September 16, 2002 Correspondence: Prof. Jayashri Kulkarni, Alfred Psychiatry Research Centre, Alfred Hospital, Commercial Road, Prahran. Vic. 3181, Australia; e-mail: jayashri.kulkarni@med.monash.edu.au     

Regulation of human alveolar macrophage- and blood monocyte-derived interleukin-8 by prostaglandin E2 and dexamethasone.

Mononuclear phagocytes are important immune effector cells that play a fundamental role in cellular immunity. In addition to their antigen-presenting and phagocytic activities, monocytes/macrophages produce a vast array of regulatory and chemotactic cytokines. Interleukin-8 (IL-8), a potent neutrophil-activating and chemotactic peptide, is produced in large quantities by mononuclear phagocytes and may be an important mediator of local and systemic inflammatory events. In this investigation, we describe the effects of prostaglandin E2 (PGE2) and dexamethasone (Dex) on IL-8 mRNA and protein expression from lipopolysaccharide (LPS)-treated human peripheral blood monocytes (PBM) and alveolar macrophages (AM). We demonstrate the dose-dependent suppression of IL-8 from LPS-stimulated PBM by PGE2. Treatment of stimulated PBM with 10(-6) M PGE2 resulted in maximal inhibition, causing 60% suppression of both IL-8 mRNA and extracellular protein levels. In contrast, PGE2 (10(-6) to 10(-8) M) did not significantly alter IL-8 mRNA or protein expression from LPS-treated AM. Treatment of LPS-stimulated PBM and AM with Dex (10(-6) to 10(-8) M) resulted in 75% decline in IL-8 mRNA and extracellular protein from either cell population. Pretreatment of PBM with PGE2 or Dex 1 or 2 h before LPS stimulation caused a significant suppression of steady-state IL-8 mRNA levels; however, administration of either of these modulators 1 or 2 h after LPS stimulation failed to have an inhibitory effect.(ABSTRACT TRUNCATED AT 250 WORDS)     

Improved performance of intravascular pO2 sensor incorporating poly(MPC-co-BMA) membrane

The first in vivo evaluation of a pO₂ sensor constructed with a novel copolymer is described. The performance of the sensor is assessed under dynamic conditions in vitro and in vivo. This sensor is more stable and reliable than the control sensor with a heparintreated polyethylene membrane.     

Immunization of adult hamsters against Clostridium difficile-associated ileocecitis and transfer of protection to infant hamsters.

In this investigation, the role of antibodies against Clostridium difficile toxins A and B in protecting hamsters against C. difficile-associated ileocecitis was examined. We also studied the transfer of protection against C. difficile-associated intestinal disease from immunized female hamsters to their infants. Adult female hamsters immunized parenterally with toxoid A or a mixture containing both toxoids A and B were protected against clindamycin-induced C. difficile-associated fatal ileocecitis. On the other hand, hamsters immunized with toxoid B or a broth filtrate from a nontoxigenic strain of C. difficile were not protected against C. difficile-induced ileocecitis. Antibody against the immunizing toxoid could be demonstrated in both the serum and the cecal contents of hamsters. Some infant hamsters from mothers immunized with toxoid A or AB were protected against C. difficile-associated ileocecitis, while infant hamsters from mothers immunized with toxoid B or a nontoxigenic broth filtrate were not protected against disease. Neutralizing antibodies to toxins A and B could be demonstrated in both maternal milk and serum, as well as in infant serum and intestinal contents. Foster-mothering experiments demonstrated that maternal protection of infants against C. difficile-associated ileocecitis was transferred to infant hamsters through breast milk. These results suggest that toxin A may play a more important role in the pathogenesis of C. difficile-associated ileocecitis in hamsters than toxin B. Furthermore, variations in the severity of C. difficile-associated illness in infants and adults may reflect the lack or presence of passively or actively acquired immunity against C. difficile toxins.     

Dopamine D1-like receptor agonists impair responding for conditioned reward in rats

The dopamine (DA) D1-like receptor agonist SKF 38393 has been reported to impair responding for conditioned reward. SKF 38393 is a partial agonist and it is possible that the impairment occurred because it prevented endogenous DA from having its full impact on the D1-like receptor. The present experiments evaluated this possibility by examining the effects of several D1-like agonists with differing efficacy at stimulating adenylate cyclase. Male rats (n = 203) were trained in a procedure with three distinct phases. During the pre-exposure phase the rats were exposed for five 40min sessions to an operant chamber containing two levers; one produced a lights-off and the other a tone stimulus (3s). This was followed by the conditioning phase, four sessions during which the levers were removed and the rats received pairings of the lights-off stimulus (80 per day) with food, presented according to a variable time 45s schedule. The test phase included two sessions during which the levers were present and the number of responses made on each lever was calculated as a ratio of the number of responses made during pre-exposure. Drugs were administered prior to each test session. No-injection and saline groups showed a higher ratio of responding for the lights-off than the tone stimulus, indicating that the lights-off stimulus had become a conditioned reward. The full D1-like agonist SKF 82958 (0.01-1.0mg/kg, s.c.) and the partial agonists SKF 81297 (0.01-1.0mg/kg), SKF 77434 (0.01-5.0mg/kg) and CY 208-243 (0.01-1.0mg/kg) impaired responding for conditioned reward at one or more of the highest doses. Results suggest that the impairments previously seen with SKF 38393 are not attributable to the partial agonist action of that drug, and continue to support the hypothesis that responding for conditioned reward is dependent on a reward-related DA signal at the D1-like receptor.