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Biomedical subjects

P M Brown

Publications and source records attributed to P M Brown.

At least 19 recordsLinked to original sources
PubMed1992

Occult fever in surgical intensive care unit patients is seldom caused by sinusitis.

Febrile intensive care unit (ICU) patients were evaluated prospectively for sinusitis. Of 598 admissions, 26 patients with transnasal cannulas, ICU stays over 48 hours, and occult fevers were identified. These 26 underwent physical examinations and sinus computed tomographic (CT) scans. Maxillary centeses and cultures were done in patients with CT abnormalities. Patients with positive scans had nasal tubes removed and received decongestants. Scans were abnormal in 19 (73%). All patients with major CT changes had positive maxillary taps. Most infections were polymicrobial; enteric bacilli were common. Fever resolved with nonoperative care in 18 (95%) patients; in only 1 patient was fever primarily from sinusitis. Sinus CT scans are often abnormal in ICU patients with occult fevers and transnasal cannulas. Pneumatic otoscopy can serve as a screening tool. Most patients respond to nonoperative management. Remote infections are often present. Although radiographic nosocomial ICU sinusitis is common, it is seldom the sole source of fever or the proximate cause of significant morbidity.

Bacterial Infections↗
PubMed1992

The selective management of small abdominal aortic aneurysms: the Kingston study.

The management of small abdominal aortic aneurysms less than 5.0 cm maximum diameter remains controversial particularly in patients who are medically fit. All patients referred with abdominal aortic aneurysms less than 5.0 cm maximum diameter were prospectively followed regardless of their fitness for operation. Two hundred sixty-eight patients had been entered into the study by December 31, 1988, and monitored until December 31, 1990, by at least two aneurysm sizings by ultrasonography, CT scanning, or both. The mean follow-up was 42 months. Operations were performed on 114 patients (if they were fit for operation) when the aneurysm reached 5.0 cm, expanded more than 0.5 cm in a 6-month period, or when the patient had significant occlusive disease requiring repair. In this group the mean annual increase in diameter was 0.9 cm. One hundred fifty-four patients were monitored without operation for a mean period of 42 months. One rupture occurred in this group. The average annual increase in diameter in the group not undergoing operation was 0.24 cm. This study supports a policy of observation for abdominal aortic aneurysms less than 5.0 cm in maximum diameter.

Adult↗
PubMed1992

Glucose turnover in type I diabetic subjects during exercise. Effect of selective and nonselective beta-blockade and insulin withdrawal.

OBJECTIVE: To assess the effect of selective beta 1-blockade (atenolol and betaxolol) and nonselective beta-blockade (propranolol) on glucose turnover in subjects with insulin-dependent (type I) diabetes mellitus during moderate exercise. RESEARCH DESIGN AND METHODS: Five subjects with type I diabetes were infused with insulin and then exercised for 1 h, after pretreatment with each of the three drugs or saline and, on a separate day, after withdrawal of insulin. Glucose turnover was measured using tritiated glucose. RESULTS: Plasma glucose, initially 9.2 +/- 0.5 mmol/L (mean +/- SE) when insulin infused and 14.0 +/- 0.8 when insulin was withdrawn, fell on exercise by 3.4 +/- 1.1 mmol/L (P < 0.05) saline, 4.0 +/- 0.8 mmol/L (P < 0.01) with betaxolol, 3.8 +/- 0.7 mmol/L (P < 0.01) with atenolol, 5.0 +/- 0.6 mmol/L (P < 0.005) with propranolol, and 1.7 +/- 1.0 mmol/L (NS) when insulin was withdrawn. Propranolol, but not the other beta-blockers, caused a significantly greater fall in glucose on exercise than during the control study. Glucose appearance rate (Ra) was similar basally and rose to an almost identical level in all five groups during exercise. Glucose disappearance rate (Rd) rose similarly during exercise, except after propranolol when the rise was significantly greater than with saline (P < 0.01). Failure of glucose to change significantly during exercise when insulin had been withdrawn was associated with the smallest rise in Rd and the highest nonesterified fatty acid concentrations. Propranolol and betaxolol, but not atenolol, reduced nonesterified fatty acids. CONCLUSIONS: We conclude that the greater fall in glucose on exercise after beta-blocking drugs is probably largely a direct effect of beta 2-blockade on muscle, increasing the exercise-induced rise in Rd glucose. This offers support to the use of beta 1-specific drugs, where beta-blockade is necessary in type I diabetes.

Adult↗
PubMed1992

Thoracoscopic transthoracic dorsal sympathectomy.

The authors report on the three patients who underwent thoracoscopic transthoracic dorsal sympathectomies by the techniques of minimal-access surgery learned from laparoscopic cholecystectomy. All three had histologic confirmation of removal of the sympathetic chain and have had an encouraging early postoperative result. The authors believe that thoracoscopic transthoracic dorsal sympathectomy can be accurately and safely performed and will become the method of choice for dorsal sympathectomy.

Adult↗
PubMed1991

Pragmatic and linguistic constraints on message formulation: a cross-linguistic study of English and ASL.

This study provides a cross-linguistic replication, using American Sign Language (ASL), of the Brown and Dell (1987) finding that when relaying an action involving an instrument, English speakers are more likely to explicitly mention the instrument if it is atypically, rather than typically, used to accomplish that action. Subjects were 20 hearing-impaired users of English and 20 hearing-impaired users of ASL. Each subject read and retold, in either English or ASL, 20 short stories. Analyses of the stories revealed production decision differences between ASL and English, but no differences related to hearing status. In ASL, there is more explicitness, and importance seems to play a more pivotal role in instrument specification. The results are related to differences in the typology of English and ASL and are discussed with regard to second-language learning and translation.

Hearing Disorders↗
PubMed1991

Integrating hearing and deaf students on a college campus. Successes and barriers as perceived by hearing students.

This study had two purposes: (1) to learn how hearing students in a mainstream college setting perceive deaf students as classmates, and (2) to discover how those perceptions influence the integration of deaf and hearing students on campus. Thirty full-time students at the Rochester Institute of Technology in Rochester, New York, were interviewed using in-depth, open-ended interview strategies. It was found that even in this setting, designed expressly to integrate deaf and hearing students, full integration did not occur. Deaf students were successfully placed on the campus with hearing students for educational purposes; however, social integration did not occur.

Attitude↗
PubMed1990

Mechanisms of delivery of liposome-encapsulated cytosine arabinoside to CV-1 cells in vitro. Fluorescence-microscopic and cytotoxicity studies.

Fluorescence microscopy and assays of the cytotoxicity of liposome-encapsulated cytosine arabinoside (araC) have been used to examine the interactions of CV-1 cells with pH-sensitive liposomes, combining phosphatidylethanolamine (PE) with oleic acid or with double-chain protonatable amphiphiles, and with pH-insensitive liposomes combining phosphatidylcholine (PC) and phosphatidylglycerol (PG). Fluorescence-microscopic observations indicate that double-chain protonatable amphiphiles remain tightly associated with pH-sensitive liposomes during incubations with CV-1 cell monolayers, and that cellular uptake of liposomes is strongly promoted by transferrin coupled to the liposome surface. Liposome-encapsulated araC showed much greater cytotoxicity toward CV-1 cells than did the free drug at equivalent concentrations under the same conditions. The cytotoxicity of encapsulated araC was strongly enhanced by liposome-conjugated transferrin and was maximal using pH-sensitive liposomes combining PE with the double-chain protonatable amphiphile N-(N'-oleoyl-2-aminopalmitoyl)serine. However, the drug was also markedly more cytotoxic when encapsulated in other types of transferrin-conjugated liposomes, including pH-insensitive PC/PG/cholesterol liposomes, than in the free form. The cytotoxicity of liposome-encapsulated araC is significantly attenuated by the nucleoside transport inhibitor nitrobenzothioinosine, and fluorescence microscopy using calcein-containing liposomes provides no evidence for efficient fusion between cellular membranes and any of the types of liposomes examined here. Based on these observations, we suggest that the major mechanism for cytoplasmic delivery of liposome-encapsulated araC is the carrier-mediated transport of drug that has been released from liposomes into the endosomal and/or the lysosomal compartments.

Animals↗
PubMed1990

External iliac artery and lumbosacral plexus injury secondary to an open book fracture of the pelvis: report of a case.

Lumbosacral plexus or external iliac artery injuries associated with pelvic fracture are reported rarely in the literature. A case involving a noncompound open book pelvic injury with diastasis of the symphysis pubis and combined ipsilateral lumbosacral plexus and external iliac artery injury is reported. Repeated clinical examination to diagnose vascular lesions with evolving pulse deficits is emphasized.

Adult↗
PubMed1989

Stability and fusion of lipid vesicles containing headgroup-modified analogues of phosphatidylethanolamine.

We have used lipid mixing, contents mixing and contents-leakage assays to characterize the divalent cation-mediated interactions of vesicles composed of various headgroup-modified analogues of phosphatidylethanolamine, PE (N- and C-2-alkylated derivatives, and analogues with increased separations of the phosphoryl and amino groups) together with a low mole percentage of phosphatidylserine (PS). Vesicles containing different structural analogues of PE exhibit marked differences, both in the threshold divalent cation concentrations that are required to initiate vesicle-vesicle interactions and in the rates of contents mixing and leakage observed at suprathresholds divalent cation concentrations. The efficiencies of divalent cation-promoted contents leakage, and to a slightly lesser extent those of contents mixing, for PS/PE (analogue) vesicles show a marked inverse correlation with the lamellar-to-hexagonal II transition temperature (TH) of the PE (analogue) component. However, the destabilization kinetics for such vesicles show no abrupt changes over the temperature range around the equilibrium TH value measured for the vesicle lipids. Vesicles combining PS with different PE analogues exhibit divalent cation thresholds for aggregation that are not correlated with the TH values of the PE (analogue) components but appear instead to be correlated with the equilibrium interbilayer separations measured in multilamellar dispersions of these species. We have identified headgroup-modified analogues of PE that can be used to prepare vesicles that fuse more rapidly under a given set of conditions, or that show a bette ratio of fusion-to-contents-leakage rates, than do PE-containing vesicles. These results may be useful both for understanding better the bases for the high fusion-supporting ability of PE and for the preparation of lipid vesicles 'tailored' for particular practical applications.

Calcium↗
PubMed1989

Microvascular invasion and survival in cancer of the oral cavity and oropharynx.

Although the presence of squamous cell carcinoma within the peritumoral vascular spaces of primary lesions of the oral cavity and oropharynx has been statistically linked to regional lymph node metastases, the association of this finding with disease control and survival has not been well demonstrated. To evaluate this relationship, we have reviewed the clinical and histopathologic features of 65 consecutive cases of previously untreated T2 or greater squamous cell carcinoma of these sites managed by simultaneous surgical treatment of the primary lesion and regional lymph nodes. Of all the histopathologic features of the primary lesion studied, vascular invasion had the greatest impact on survival, as confirmed by both univariate and multivariate analysis. In addition, vascular invasion correlated statistically with local recurrence, neck recurrence, and distant metastasis.

Adult↗
PubMed1989

The skull base and nasopharynx in Down's syndrome in relation to hearing impairment.

Children with Down's syndrome have a higher incidence of middle ear effusion than normal children. Twenty-eight patients with Down's syndrome and 33 age and sex-matched normal controls were studied. They were subdivided into 2 further matched groups on the basis of having normal or impaired hearing. Each underwent pneumatic otoscopy, audiometry and lateral head and neck radiography. This study examines radiological parameters to determine whether skeletal or soft tissue factors within the skull base or nasopharynx could be implicated as a cause or diagnostic feature of Eustachian tube dysfunction. The nasopharynx tended to be smaller in those with Down's syndrome and this resulted in a reduction in the airway size due to encroachment by the soft tissues. The angle between the base of skull and hard palate was significantly less acute in those with Down's syndrome and in those with hearing loss.

Child↗
PubMed1988

Identification and treatment of risk factors for coronary heart disease in general practice: a possible screening model.

A screening programme for the identification of risk factors for coronary heart disease in all patients aged 25-55 years in a general practice population was studied. The identification of risk factors included measurement of obesity, blood pressure, hypercholesterolaemia, and urinalysis, together with questions about family history, cigarette smoking, alcohol intake, and lifestyle. The patients with identified risk factors were invited to attend a lifestyle intervention clinic organised by the practice nurses and run by the health visitors, with the help of the local authority dietitian. Of 2646 (62%) patients who attended for screening, 78 (64%) of the 121 shown to have a high cholesterol concentration experienced a drop in cholesterol concentration. The mean fall in cholesterol concentration in the 78 patients who showed a positive response to intervention was 1.1 mmol/l. The study was intended as a possible flexible model for screening for coronary heart disease in general practice that could be complemented rather than replaced by opportunistic screening. The issues of organisation, cost, manpower, nonattendance, and effectiveness in a busy general practice environment are discussed.

Adult↗
PubMed1987

Novel fluorescent phospholipids for assays of lipid mixing between membranes.

A series of fluorescent phospholipids has been synthesized, by a general and versatile procedure, with various fluorescent groups attached to the methyl-terminal half of one acyl chain in an otherwise normal phospholipid structure. Phospholipids labeled with (dialkylamino)coumarin moieties, and to a slightly lesser extent those labeled with a bimane group, exhibit a strong and stable blue fluorescence in phospholipid dispersions that is relatively insensitive to the physical state of the lipid phase. The fluorescence of these labeled phospholipids is efficiently quenched by resonance energy transfer to lipids labeled with a [[(dimethylamino)phenyl]azo]phenyl or a methyl(nitrobenzoxadiazolyl)amino group when these acceptors are incorporated into the same bilayer as the donor species. Acyl chain labeled phospholipid probes, both of whose chains are at least sixteen carbons in length, exchange extremely slowly between lipid vesicles (less than 1% exchange/h). These properties allow various donor-acceptor combinations of probes to be employed in sensitive and reliable assays of lipid mixing accompanying membrane fusion. We demonstrate that, in two particularly demanding applications (assays of the calcium-mediated coalescence of phosphatidylserine vesicles and of the proton-triggered coalescence of phosphatidylethanolamine vesicles), some combinations of acyl chain labeled probes offer substantial advantages over the commonly used N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)phosphatidylethanolamine/N-(l issamine rhodamine B sulfonyl)phosphatidylethanolamine pair to monitor accurately the progress of lipid mixing between vesicles.

Fluorescent Dyes↗
PubMed1987

Supersensitivity to both tyramine and noradrenaline in diabetic autonomic neuropathy.

Cardiovascular responses to intravenously infused tyramine and noradrenaline were measured in five normal subjects, five insulin-dependent diabetics and five insulin-dependent diabetics with autonomic neuropathy. Tyramine infusion produced a statistically significant increase in systolic blood pressure (BP) in the autonomic neuropaths only (p less than 0.001). No change occurred in diastolic BP. Noradrenaline infusion produced a statistically significant increase in systolic BP in the normal subjects (p less than 0.01) and in the autonomic neuropaths (p less than 0.001). The increase in systolic BP in the neuropaths was significantly greater (p less than 0.001) than in normal subjects. Diastolic BP rose significantly only in the normal subjects (p less than 0.05). There was no change in heart rate in response to either agent. Thus super-sensitivity to noradrenaline occurred in patients with diabetic autonomic neuropathy indicating post-denervation hypersensitivity. Tyramine hypersensitivity also occurred indicating that denervation is not complete and suggesting dysfunction at a pre-synaptic level.

Adult↗
PubMed1987

Patterns of marijuana and alcohol use attitudes for Pennsylvania 11th graders.

For a 6-year period 30,000 11th graders in Pennsylvania public schools answered questions regarding their situational use of marijuana and the most popularly consumed beverage alcohol, beer. Comparing the item means for the survey responses between 1978 and 1983 supports other national data indicating a significant decline in the use of marijuana by high school students. A new finding is that 11th graders' willingness to drink beer with their friends has declined significantly, beginning in 1982, as has their willingness to drink and drive, beginning in about 1981. These changes may be related historically to the intensive public information and education efforts begun during the same time period.

Adolescent↗
PubMed1987

Gastroepiploic-coronary anastomosis. A viable alternative bypass graft.

Although increasing use is being made of arterial grafts (the internal mammary arteries) for direct myocardial revascularization, it is frequently not possible to reach the posterior surface of the heart with the internal mammary as either a pedicle or a free graft. Since June 1984 we have used the right gastroepiploic artery in nine patients as a pedicle graft to the distal right coronary artery (four patients), the posterior descending artery (three patients), and the distal circumflex branches (two patients). Eight patients survived the operation. Celiac axis opacification confirmed patency in six and coronary angiography strongly suggested patency in the remaining two. All survivors are functionally in New York Heart Association Class I or II. The early angiographic and clinical results demonstrate the feasibility of using the right gastroepiploic artery as a bypass graft to coronary vessels on the posterior surface of the heart when traditional conduits are unsuitable. If its long-term patency as a living arterial graft is similar to that of the internal mammary arteries, the gastroepiploic artery may become the coronary bypass graft of choice for the distal right coronary and circumflex systems.

Aged↗
PubMed1986

Role of head group structure in the phase behavior of amino phospholipids. 1. Hydrated and dehydrated lamellar phases of saturated phosphatidylethanolamine analogues.

Analogues of dimyristoylphosphatidylethanolamine (DMPE) have been prepared with head groups modified by N-alkylation, alkylation of carbon 2 of the ethanolamine group, or interposition of extra methylene segments between the phosphoryl and amino groups. The phases formed by these lipids in aqueous dispersions have been examined by high-sensitivity differential scanning calorimetry and Raman spectroscopy. All of the DMPE analogues examined, excepting N-methyl-DMPE but including N-ethyl-DMPE, form hydrated gel phases that are metastable with respect to a dehydrated "high-melting" solid phase that has been observed previously for DMPE itself. The properties and the conditions of formation of this high-melting phase are qualitatively distinct from those of the "subgel" phase, which is observed for dipalmitoylphosphatidylcholine and for some of the DMPE analogues examined in this study. The high-melting phases of different DMPE analogues all exhibit similarly tight packing of the acyl chains, which however do not pack according to a single type of subcell that can be universally and specifically associated with this phase. Increasing the size of the PE head group invariably decreases the melting temperature of the hydrated gel phase, even when the normal hydrogen-bonding capability of the head group is preserved. By contrast, addition of larger alkyl substituents to either the amino group or carbon 2 of the ethanolamine moiety substantially increases the transition temperature of the high-melting solid phase, indicating that the contributions of the head group to the energies of the hydrated gel and the high-melting phases are fundamentally different. Our results suggest that the head group structural requirements for a neutral phospholipid to form stable hydrated bilayers are rather stringent, a fact that may explain the overwhelming predominance of only a few such head group structures in most natural membranes.

Calorimetry, Differential Scanning↗