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Biomedical subjects

S M Weiss

Publications and source records attributed to S M Weiss.

At least 37 records · Page 2Linked to original sources
PubMed1995

Physiologic evaluation of bronchial asthma. Why objective testing is essential.

Physiologic evaluation of bronchial asthma is extremely valuable. Simple objective measurements of expiratory airflow and lung volume help physicians determine disease status and monitor patient response to therapy. More elaborate measurements of pulmonary function are not commonly needed in primary care practice. The three case studies described in this article show that objective assessment of lung function is critical in effective treatment of asthma.

Adult↗
PubMed1994

Enteritis necroticans with midgut necrosis caused by Clostridium perfringens.

Enteritis necroticans is a necrotizing process manifesting as segmental gangrene of the bowel, triggered by Clostridium perfringens toxins under specific dietary conditions. It is a rare disease in developed countries and is probably underdiagnosed. A case of enteritis necroticans presenting with midgut necrosis with sepsis and hemolysis is reported herein. Bacteriologic culture of blood and peritoneal content revealed C perfringens. Dietary history, including the ingestion of meat together with sweet potatoes, should increase clinical suspicion of enteritis necroticans. Early recognition and timely surgical intervention are required for successful treatment. Clinicians are encouraged to be aware of this clinically fulminant yet rarely recognized surgical entity.

Clostridium Infections↗
PubMed1994

Outcome from respiratory failure.

A physician's assessment of the probable outcome of an episode of respiratory failure should be based on a combination of survival data from large studies and specific knowledge about the individual case in question. Clearly, mortality rates in cases of ARF are influenced by a number of factors. In general, only a minority of patients with ARF complicating COPD require mechanical ventilation. In these cases, mortality often is related to the nature of the precipitating illness and the severity of the patient's underlying chronic respiratory disease. The long-term prognosis in patients with COPD who survive an episode of ARF is related primarily to the severity of the patient's underlying disease. Acute mortality is higher in patients with ARDS than in patients with ARF complicating COPD. Although a significant number of ARDS patients die of their underlying illness, mortality in others more commonly appears to be related to sepsis and multiple organ failure rather than end-stage respiratory disease. Pulmonary function in survivors of ARDS is quite variable, and may be related to the severity of the acute episode. ARF has a particularly poor prognosis when associated with certain underlying illnesses such as hematologic malignancy.

Acute Disease↗
PubMed1994

Splenic abscess.

The character and management of splenic abscess has changed in the past decade. The condition is more frequent, diagnosis is more easily established, and survival is more likely. Seven patients with splenic abscess from 1981-1992 were retrospectively reviewed. These patients had different etiologies for their splenic abscess, including hematogenous bacteria spread, contiguous spread, and previous history of trauma to the spleen or left upper quadrant. Most patients presented clinically with fever, left upper quadrant tenderness, and leukocytosis. All patients underwent CT scanning that was reliably diagnostic. All seven patients underwent splenectomy. Six of the seven patients were discharged from the hospital. We conclude that CT scan remains the gold standard for definitive diagnosis of splenic abscess, and splenectomy is very effective therapy.

Abscess↗
PubMed1994

Acute inhalation injury.

Toxic inhalants cause injury through a variety of different mechanisms, including direct irritation of the respiratory tract mucosa, asphyxiation, and systemic absorption of the toxin. The nature and extent of the acute injury depends on the inhalant's water solubility, aerodynamic features, pH, and concentration. In addition, a patient's underlying respiratory function may affect the clinical response. Smoke inhalation is a particularly challenging clinical problem because patients often are exposed to a large number of inhaled toxins and may suffer thermal injury to the respiratory tract as well. Several chronic respiratory problems have been identified following acute inhalation injuries. Chronic airflow obstruction has been reported in patients exposed to ammonia, chlorine, nitrogen dioxide, and sulfur dioxide; bronchiolitis obliterans may follow exposure to nitrogen dioxide and sulfur dioxide. Inhalation injuries can be difficult to manage because exposures occur infrequently, and the exact toxic agents involved often are not known immediately. Prevention of occupational exposures remains a cornerstone in the overall management of inhalation injuries.

Burns, Inhalation↗
PubMed1993

Subordination stress: behavioral, brain, and neuroendocrine correlates.

In mixed-sex rat groups consistent asymmetries in offensive and defensive behaviors of male dyads are associated with the development of dominance hierarchies. Subordinate males can be differentiated from dominants on the basis of both agonistic and non-agonistic behaviors, wound patterns, weight changes. Their behavior changes suggest chronic defensiveness and are also broadly isomorphic to many of the symptoms of depression; their voluntary alcohol consumption increases, and their life-spans are shortened. Both subordinate and dominant males tend to show organ change compared to non-grouped controls, with adrenal and spleen enlargement and thymus reduction. However, these changes appear to be more marked in subordinates, and only subordinates show reduced testes weights. Basal corticosterone (CORT) levels were sharply higher, and plasma testosterone (T) sharply lower, in subordinates compared to both dominants and controls, and reduced corticosterone binding globulin further enhanced free CORT for subordinates particularly. Many subordinates failed to show a normal CORT response to restraint stress. Subordinates also appear to show widespread changes in serotonin systems, with increased 5-HIAA/5-HT ratios in a number of brain areas, and alterations of 5-HT1A receptor binding at some sites. These changes suggest that subordination, a common and consistent feature of life for many animals living in social groups, may be a particularly relevant model for investigating the behavioral, neural and endocrine correlates of chronic stress.

Aggression↗
PubMed1993

False negative breast biopsy for palpable mass.

Open breast biopsy is considered to be the most reliable method for the diagnosis of breast cancer in patients with palpable masses. Rarely, after a breast biopsy has been reported to be benign, cancer will be identified at the site of the biopsy. Eight patients were reviewed in whom breast cancer was demonstrated at the site of a previously negative biopsy at intervals ranging between 4 months and 3 years after the original, negative biopsy. Several possible explanations exist to account for this occurrence. The surgeon must be aware that the presence of a mass at the site of prior breast biopsy may be an indication for repeat excision.

Biopsy↗
PubMed1993

Immunological responses of breast cancer patients to behavioral interventions.

This article reports the results of an 18-month study of immune system and psychological changes in stage 1 breast cancer patients provided with relaxation, guided imagery, and biofeedback training. Thirteen lymph node negative patients who had recovered from a modified radical mastectomy were randomly assigned to either an immediate treatment or a delayed treatment control group. Multiple pre-post psychological measures were performed. Significant effects were found in natural killer cell (NK) activity (p < .017), mixed lymphocyte responsiveness (MLR) (p < .001), concanavalin A (Con-A) responsiveness (p < .001), and the number of peripheral blood lymphocytes (PBL) (p < .01). No significant psychological changes were detected; however, reductions were seen in psychological inventory scales measuring anxiety. The results show that behavioral interventions can be correlated with immune system measures, thereby replicating the results of an earlier pilot study from our Center. Discussion is provided on differential T-cell and B-cell responsiveness to behavioral interventions.

Adult↗
PubMed1993

Complications of fiberoptic bronchoscopy in thrombocytopenic patients.

STUDY OBJECTIVE: To determine the risk of epistaxis and pulmonary hemorrhage due to fiberoptic bronchoscopy (FOB) and bronchoalveolar lavage (BAL) in the presence of thrombocytopenia. DESIGN: Prospective study of all patients undergoing FOB with BAL with a 4.9-mm-diameter bronchoscope after bone marrow transplantation (BMT) during a 6-month period. SETTING: A single BMT center. PATIENTS: Forty-seven BMT recipients undergoing 66 FOB with BAL. Thrombocytopenia (platelets < 100,000/ml) was present in 58 (88 percent). Platelets were < 50,000/ml in 44 (67 percent) and < 20,000/ml in 13 (20 percent). In the thrombocytopenic patients, FOB with BAL was transnasal in 37 (64 percent), transoral in 5 (9 percent), and via endotracheal tube in 16 (28 percent). INTERVENTIONS: Fiberoptic bronchoscopy with BAL using a bronchoscope (Pentax FB-15H) (4.9-mm diameter). In one case, a pediatric bronchoscope (Pentax FB-10H; 3.5-mm diameter) was used in a 7-year-old patient. MEASUREMENTS AND RESULTS: The BAL was diagnostic in 22 of 47 patients studied (47 percent). Complications occurred in 7 of 58 (12 percent) thrombocytopenic patients (epistaxis and/or hemoptysis, 4; bradycardia, 2; bronchospasm, 1) of which all but 1 were minor and self-limiting. One life-threatening complication of severe epistaxis occurred during a transoral FOB in a patient with prior epistaxis (platelet count, 18,000/ml). One of 8 (13 percent) nonthrombocytopenic patients had hemoptysis. No patient had worsening fever or oxygenation at 4 h and no patient displayed worsening radiographic infiltrates suggestive of pulmonary hemorrhage attributable to the BAL at 24 h. CONCLUSIONS: We conclude that transnasal FOB in thrombocytopenic patients was safe, being associated with minor airway bleeding in 3 of 37 patients (8 percent). In conclusion, FOB with BAL, even via the transnasal route, may be performed with relative safety despite the presence of significant thrombocytopenia.

Adult↗
PubMed1993

Transmembrane segment prediction from protein sequence data.

We consider the automated identification of transmembrane domains in membrane protein sequences. 324 proteins (containing 1585 segments) were examined, representing every protein in the PIR database having the transmembrane domain feature annotation. Machine learning techniques were used to evaluate the efficacy of alternative hydrophobicity measures and windowing techniques. We describe a simpler measure of hydrophobicity and a new variable window size concept. We demonstrate that these techniques are superior to some previous techniques in minimizing the segment error rate. Using these new techniques, we describe an algorithm that has a 7.9% segment error rate on the sampled proteins, while classifying 16.7% of the amino acid residues as transmembrane.

Algorithms↗
PubMed1992

Surgical complications of intraoperative radiation therapy: the Radiation Therapy Oncology Group experience.

Intraoperative radiotherapy (IORT) is being used with increasing frequency in many institutions in the United States but little is known about the surgical complication rates. The Radiation Therapy Oncology Group initiated three prospective studies in IORT in 1986 and we report here the experience in advanced malignancies of the stomach, pancreas, and rectum. The incidence and nature of major surgical complications were reviewed and presented with their implications in regard to future IORT trials. Two hundred twenty-seven patients were entered on three studies by 20 participating institutions between 1985 and 1989. One hundred twenty-nine patients received IORT while 98 patients were found to have too advanced disease to be benefited by IORT and underwent palliative surgical procedures only. IORT doses ranged from 12-22 Gy and bowel anastomoses were not irradiated. Wound infection in the IORT group was 6% vs. 2% in the non-IORT patients but this was not significant at the P = 0.05 level. Other complications included anastomotic leak (n = 5), operative bleeding (n = 10), pancreatitis (n = 2), and were not statistically different in the IORT and non-IORT groups. The mortality rate for the IORT and non-IORT groups combined was 1.8%. This large multi-institutional experience in patients with advanced malignancy demonstrates that patients receiving IORT do not have a higher surgical complication rate than those not receiving IORT. Long-term survival data await the implementation of Phase III trials in advanced intra-abdominal malignancy.

Combined Modality Therapy↗
PubMed1992

Morphine attenuates antipredator ultrasonic vocalizations in mixed-sex rat colonies.

Mixed-sex groups of laboratory rats living in a visible burrow system (VBS) emit 18-27 kHz ultrasound and retreat to the burrow when a cat is placed in the open area of the VBS. The total duration of ultrasonic vocalizations was reliably reduced by pretreatment with 5 mg/kg morphine. In a subsequent study using male-female colony pairs, presentation of a cat to individual rats in the absence of their colony mate indicated significant gender differences in base frequency, degree of emission, and characteristics of pulses elicited. Specifically, females showed a greater number and duration of vocalizations, of higher frequency (kHz), and with shorter individual pulse durations than males. In the same study, morphine (5 mg/kg) produced a general decrease in the level of ultrasonic emissions in both sexes, reduced the mean base frequency (kHz), and increased the mean duration of individual pulses. These data suggest that endogenous opioid mechanisms may be involved in the mediation of ultrasonic vocalization in response to a predator, and are discussed with reference to known involvement of such systems in defensive responding.

Animals↗
PubMed1992

Do changes in transcardiac impedance modulation correlate with haemodynamic status?

Implantable cardiac pacemakers and defibrillators have the ability to revert a variety of arrhythmias to normal sinus rhythm. For correct operation, such devices require accurate arrhythmia classification. Arrhythmia classification by these devices could be improved with the addition of a suitable haemodynamic sensor. This study investigated the use of transcardiac impedance for haemodynamic sensing. Ventricular fibrillation, ventricular tachycardia, electro-mechanical dissociation and five rates of ventricular pacing, each having a different associated level of haemodynamic compromise, were induced in each of seven mongrel dogs. The amplitude responses of the modulations of transcardiac impedance were compared with those of arterial pulse pressure (an established measure of haemodynamic status), and changes in cycle length. The correlation coefficient for changes in transcardiac impedance modulation amplitude and arterial pulse pressure was found to be 0.89. For transcardiac impedance modulation amplitude and cycle length, the correlation coefficient was 0.77, and for arterial pulse pressure and cycle length, the correlation coefficient was 0.85. In the acute anaesthetised dog, changes in the amplitude of transcardiac impedance modulations were shown to reflect different levels of haemodynamic status.

Animals↗
PubMed1991

Twenty-two kHz alarm cries to presentation of a predator, by laboratory rats living in visible burrow systems.

When a cat was presented to groups of 3 male and 2 female laboratory rats in the open area of a visible burrow system, the rats retreated to the burrow system and showed high levels of 18-24 kHz ultrasonic cries during the cat presentation and for 30 min following removal of the cat. Latency to make ultrasonic vocalizations, durations of these vocalizations, and duration in the burrow systems were all strikingly and reliably different during and after cat exposure in comparison to similar periods with a control (stuffed cat toy) stimulus. However, when individual rats were exposed to a cat in an open area of similar size, ultrasonic cry production was minimal. Also rats exposed individually to a cat in an apparatus providing an escape chamber similarly showed no ultrasonic cries, indicating that concealment per se is not a sufficient condition for their appearance. These results suggest that the production of ultrasonic vocalizations during and after exposure to a predator is greatly facilitated by the presence of familiar conspecifics, and may serve as alarm cries. While the alarm cry hypothesis also suggests a possible function for 18-24 kHz ultrasounds in the context of copulation and intraspecies aggression, the sonographic and functional relationships among the cries emitted in these different situations remain to be analyzed.

Animals↗
PubMed1991

"Paradoxical" effects of morphine on antipredator defense reactions in wild and laboratory rats.

In a Fear/Defense Test Battery, measuring defensive reactions to a present, approaching and contacting predator, the highest dose of morphine tested (7.5 mg/kg) reliably reduced vocalization to dorsal contact, to vibrissae stimulation, and to an anesthetized conspecific in laboratory-bred wild R. norvegicus. Except for a dose-dependent reduction in flinch/jump reactions to dorsal contact (taps), other defensive behaviors (flight, freezing, etc.) were not reliably altered by morphine treatment (0, 1.0, 2.5, 7.5 mg/kg). Vocalization responses to vibrissae stimulation in wild-trapped R. rattus were reliably increased following naloxone (1.0 and 10.0 mg/kg) administration, lending support for opiate receptor involvement in the mediation of defensive vocalization. In the Anxiety/Defense Test Battery, measuring defensive reactions to situations associated with a predator (cat) or with cat odor, laboratory rats showed no decrease in defensive behavior with morphine (0, 1.0, 5.0 mg/kg). In direct contrast to the above findings, the effects of morphine treatment in this test battery suggested a generalized increase in defensiveness to noncontacting and nonpainful threat stimuli. These effects included a decrease in time spent near the cat compartment, with a complementary increase in time spent at maximum distance, a decrease in transits between these sections, an increase in crouching, and a decrease in grooming and rearing. This pattern of results suggests that morphine may have two opposing effects on defensive behavior, a generalized enhancement, together with a more specific reduction of responses to tactile or painful stimulation. A very widespread pattern of reliable sex or sex x drug effects in the Anxiety/Defense Test Battery was in good agreement with previous reports of sex differences in these tests, with females generally more defensive than males. Consonant with previous findings, no reliable sex differences were found with the Fear/Defense Test Battery, although several values approached an acceptable level of statistical significance.

Animals↗
PubMed1991

Can changes in transcardiac impedance appropriately detect ventricular fibrillation?

Transcardiac impedance, as measured between two implanted defibrillator patches, has been shown to vary in peak-to-peak magnitude in response to the contractions of the ventricles. These variations in transcardiac impedance are known as delta Z. This study was aimed at determining if there was a significant change in the magnitude of delta Z between that during normal sinus rhythm, that during ventricular fibrillation (VF), and if this change could be used as a detector of the onset of VF. This study was performed acutely on 14 anesthetized dogs.

Animals↗