The pathophysiology of tension pneumothorax in ventilated swine

Patients with possible acute renal obstruction often undergo numerous types of radiological examinations. Renal Doppler ultrasound is a quick and noninvasive way to assess for physiological and hemodynamic changes that accompany acute obstruction. The renal Doppler study may provide unique data not available from conventional sonography. Most, but not all, clinical and laboratory studies regarding Doppler of acute renal obstruction have reported encouraging results. As limitations to the Doppler examination in this clinical setting are delineated, a proper role for renal Doppler will continue to emerge.     

Brainstem mediates diazepam enhancement of palatability and feeding: microinjections into fourth ventricle versus lateral ventricle

The hypothesis that benzodiazepine-induced hyperphagia is due to a specific enhancement of the palatability of foods has been supported by previous 'taste reactivity' studies of affective (hedonic and aversive) reactions to taste palatability. Diazepam and chlordiazepoxide enhance hedonic reactions of rats (rhythmic tongue protrusions, etc.) to sweet tastes in a receptor-specific fashion. A role for brainstem circuits has been indicated by a previous demonstration of the persistence of the taste reactivity enhancement by diazepam after midbrain decerebration. The present study examined whether benzodiazepine brainstem receptors are the chief substrates for palatability enhancement even in intact brains. We compared the effectiveness of benzodiazepine microinjections to elicit feeding and enhance hedonic reactions when delivered into either the lateral ventricle (forebrain) or the fourth ventricle (brainstem) of rats. The results show diazepam is reliably more effective at eliciting feeding and enhancing positive hedonic reactions to oral sucrose when microinjections are made in the fourth ventricle than in the lateral ventricle. We conclude that brainstem neural systems containing benzodiazepine-GABA receptors are likely to be the chief substrates for benzodiazepine-induced palatability enhancement.     

Identification and neutralization of biological activities in the venoms of Loxosceles spiders

The biological activities of the venom of three species of spiders of the genus Loxosceles were studied (L. gaucho, L. laeta and L. intermedia). The dermonecrotic and lethal activities are shared by all three Loxosceles venoms. Only low levels of proteolytic, myotoxic and phospholipase A2 activities were demonstrable even when a large amount of venom was used. No direct hemolytic activity was detected. L. intermedia venom was the most lethal (LD50 0.48 mg/kg), the L. laeta venom was the least lethal (LD50 1.45 mg/kg) whereas L. gaucho venom showed an intermediate value (LD50 0.74 mg/kg). The anti-Loxosceles serum used (anti-arachnidic serum) was able to neutralize the most important activities (i.e., dermonecrotic and lethal activities) of the three venoms. SDS-PAGE and immunoblotting using the anti-arachnidic serum showed that almost all venom antigens were recognized by this antiserum. The possible mechanisms of action of the Loxosceles venom are discussed.     

The relationships among nursing diagnoses in discharge planning for patients with lung cancer

An explanatory study was designed to investigate whether nursing diagnoses present at discharge from the hospital accurately describe the complexity of care required in the community. A sample of 196 patients with lung cancer referred to community agencies at discharge was described by types of nursing diagnoses; types of agencies needed and services required; and by age, gender, race, economic status, and hospital length of stay. Using multiple logistic regression, a model for home care referral resulted in four significant predictor diagnoses: altered nutrition: less than body requirements, bathing/hygiene self-care deficit, high risk for infection, and high risk for injury. The model for hospice referral resulted in four significant predictor diagnoses: anticipatory grieving, impaired skin integrity, high risk for impaired skin integrity, and pain. The data suggest that the nursing diagnoses described the discharge planning needs, which predicted the type of agency referral needed.     

Emerging role of laparoscopy in the diagnosis of lymphoma

PURPOSE: The results of laparoscopic procedures on patients with suspected or known lymphoma were analyzed to review the application and define the role of laparoscopy in lymphoma. PATIENTS AND METHODS: The hospital records of 94 patients who underwent 101 procedures between June 1993 and October 1996 were reviewed for demographic and clinicopathologic information. RESULTS: The procedure was diagnostic in 85 patients, either at primary presentation (48 patients), possible relapse (21 patients), in the course of treatment (eight patients), or of a liver lesion (eight patients). In the remaining 16 patients, it was used to stage possible intraabdominal disease. Twenty-seven patients had a previous unsuccessful diagnostic procedure. There were no operative deaths and eight postoperative complications (8%). The laparoscopy revealed non-Hodgkin's lymphoma (NHL) in 48 patients, Hodgkin's disease (HD) in 14 patients, other neoplastic conditions in six patients, and benign conditions in 33 patients. There was adequate information in all procedures in which lymphoma was diagnosed for treatment decisions. There was one false-negative and one nonresult for technical reasons. Ten patients commenced chemotherapy before discharge after a median delay of 3.5 days. In five of 24 patients (21%) with recurrent or persistent lymphoma, the precise diagnosis was significantly different from the original one. CONCLUSION: From our experience, laparoscopy can safely provide tissue samples of suspected lymphoma for full diagnostic analysis. It should be considered when percutaneous biopsy is not technically possible, when chromosomal or genetic analysis is needed for treatment decisions, or when the results of percutaneous biopsy are inadequate to make therapeutic decisions.     

The role of mucosal biopsy in the diagnosis of chronic diarrhea: value of multiple biopsies when colonoscopic finding is normal or nonspecific

The CTLA4 receptor is a CD28 homologue which induces inhibitory effect on activated T-cells. Peripheral T-cells proliferate spontaneously in CTLA4-deficient mice. These results led to an analysis of CTLA4 expression in human lymphomas (n = 82) including Hodgkin's disease (HD) and non-Hodgkin's lymphomas (NHLs), using immunohistochemistry. CTLA4 was present in neoplastic cells from most (10/11) T-cell malignancies, except for anaplastic and lymphoblastic subtypes (0/4). Malignant B-cells from rare (3/55) B-NHLs (all of follicular subtype) were also CTLA4-positive. Other B-NHLs (52/55) were negative in malignant B-cells and occasionally positive in T-cells. Reactive small lymphocytes, but not Reed-Sternberg cells, from all (12/12) HD cases were strongly CTLA4-positive. The CTLA4 ligands CD80 and CD86 were simultaneously expressed in most CTLA4-negative lymphoma cases. CTLA4 is thus expressed either in the reactive or in the malignant cell populations, depending on the lymphoma subtype. These results provide new insights leading towards therapeutic strategies based either on enhancement of anti-tumour immunity by CTLA4 blockade in reactive lymphocytes or on triggering of a CTLA4-mediated inhibitory pathway in lymphoma cells.     

Urinary free cortisol in the assessment of hydrocortisone replacement therapy

The protective effect of astrocytes on hippocampal neurons against kainate-induced toxicity was investigated using neuron-specific enolase as an indicator of neuronal death. Astrocyte-rich and astrocyte-poor mixed rat hippocampal cultures were submitted to various concentrations of kainate. At each kainate concentration, the amount of NSE released by neurons was significantly greater in astrocyte-poor than in astrocyte-rich cultures (p < 0.05). This protective effect was not observed when neuronal survival was tested on astrocyte-poor cultures in astrocyte-conditioned culture medium with or without 10(-4) M kainate. In conclusion, astrocytes significantly attenuate kainate toxicity on hippocampal neurons, and this effect is not mediated by a diffusible factor.     

Responses of cutaneous A-fiber nociceptors to noxious cold

Responses of cutaneous nociceptors to natural stimuli, particularly mechanical and heat stimuli, have been well documented. Although nociceptors are excited by noxious cold stimuli, there have been few studies of their stimulus-response functions for cold stimuli over a wide range of stimulus temperatures. Furthermore, the proportion of nociceptors excited by noxious cold is not clear. In the present study, we examined responses of mechanosensitive A delta-nociceptors and low-threshold mechanoreceptors to a wide range of cold stimuli that included stimulus temperatures <0 degrees C. Electrophysiological recordings were made from single primary afferent fibers in the saphenous nerves of anesthetized rats. Cutaneous sensory receptors were classed according to their conduction velocity and subgrouped functionally according to their responses evoked by mechanical, heat, and cold stimuli (0 degrees C). Responses evoked by a wide range of cold stimulus intensities that included stimuli considered innocuous and noxious (painful) were then assessed. Stimuli of 20 to -20 degrees C were delivered to the receptive field via a 1-cm2 contact thermode from a base temperature of 32 degrees C. Stimuli were applied in descending order of 2 degrees C decrements. Stimulus ramp rate was 5 degrees C/s, and stimulus temperatures were applied for a duration of 10 s. A total of 90 A fibers was studied, of which 61 were nociceptors and had conduction velocity in the A delta-range (2-30 m/s). Nociceptors were classed initially as mechanical, mechanoheat, and mechanocold nociceptors. The remaining 29 fibers were low-threshold mechanoreceptors with conduction velocity in the A delta- or A beta-range (>30 m/s). These were subgrouped according to their adaptive properties as slowly or rapidly adapting, and according to whether they were excited by hair movement (hair follicle afferent fibers). All nociceptors were excited by noxious cold. Only 30% of nociceptors were considered sensitive to cold on initial classification with the use of a cold stimulus of 0 degrees C. However, all nociceptors were excited by stimulus intensities <0 degreesC. Response thresholds for cold ranged from 14 to -18 degrees C (-4.6 +/- 1.07 degrees C, mean +/- SE). The total number of impulses, discharge rate, and peak discharge increased monotonically as intensity of cold stimuli increased. Power functions were used to determine the rate at which the number of impulses increased as stimulus intensity increased. The slopes of power funcions ranged from 0.12 to 2.28 (mean 1.07 +/- 0.13). Most mechanoreceptors were not excited by cold stimuli. The only types of mechanoreceptors that responded reliably to cold stimuli were the slowly adapting mechanoreceptors. Responses usually occurred during the temperature ramp when the skin temperature was decreasing. There was no evidence that mechanoreceptors encoded the intensity of cold stimuli at intensities above or below 0 degrees C, because evoked responses did not increase with intensity of cold stimuli. It is concluded that the proportion of cutaneous A delta-nociceptors excited by noxious cold stimuli has been underestimated in previous studies. All nociceptors were excited by stimulus temperatures <0 degrees C and encoded the intensity of cold stimuli. It is therefore likely that cutaneous A delta-nociceptors contribute to the sensation of cold pain, particularly pain produced by stimulus temperatures <0 degrees C.     

Cholesteatoma in children

Cholesteatoma in children falls into two main categories: congenital and acquired. Though they present in different ways, both are potentially destructive lesions that are managed surgically. The goals of treatment are to eradicate keratinizing squamous epithelium from the temporal bone and to preserve or restore hearing. These children need to be followed closely by the pediatric otolaryngologist to prevent and control recurrent disease.     

Further studies on the endocytic activity of Tritrichomonas foetus

The endocytic activity of Tritrichomonas foetus was studied at the ultrastructural level using gold-labeled macromolecules (bovine lactoferrin, human and bovine transferrin, bovine albumin, human low-density lipoprotein, horseradish peroxidase, and protein A). All macromolecules were ingested by the protozoan. Binding experiments showed that only bovine lactoferrin bound to the parasite surface in a process that could be inhibited by the unlabeled protein, suggesting that it binds and is internalized via receptors. Label-fracture experiments showed that the receptors were distributed in clusters that did not colocalize with intramembranous particles. Kinetics analysis of the internalization of bovine lactoferrin and horseradish peroxidase, associated with the cytochemical detection of acid phosphatase, revealed that proteins were rapidly ingested through small uncoated vesicles and delivered to acid phosphatase-containing compartments. The colocalization of gold-labeled proteins and reaction product indicative of enzyme activity was confirmed by electron spectroscopic imaging. Simultaneous incubation of cells in the presence of two proteins labeled with gold particles of different diameters showed that they were ingested through the same pathway and were concentrated into cytoplasmic vacuoles corresponding to lysosome-like organelles. These data suggest that the endocytic process in T. foetus is very rapid and that the intracellular pathway for receptor-mediated and fluid-phase endocytosis seems to be the same.