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Biomedical subjects

S Evans

Publications and source records attributed to S Evans.

At least 289 records · Page 16Linked to original sources
PubMed1988

The effect of transdermal estradiol on hormone and metabolic dynamics over a six-week period.

Seventeen healthy postmenopausal women who had subjectively noted eight or more hot flashes per day and who objectively demonstrated four or more vasomotor flushes of 1.0C or more during eight hours of continuous thermography were studied. They were randomly allocated in a double-blind fashion to either 50 micrograms/day of transdermal estradiol (E2) patch or placebo. Application of the first patch was followed immediately by repeat eight-hour thermography, with hourly measurements of E2 and luteinizing hormone (LH). In the transdermal E2 group only, significant elevations of E2 (mean 91 pg/mL) were noted at two hours, and LH was suppressed after eight hours (P less than .05). There was no immediate effect on vasomotor flushes. Treatment was continued for six weeks, with daily subjective recording of hot flash frequency. Patients on transdermal E2 reported a significant (P less than .001) fall in hot flashes over four weeks, after which the rate stabilized. An initial decline in the placebo group was not statistically different from baseline. Eight-hour thermography was repeated after six weeks of treatment. Patients on transdermal E2 demonstrated an 85% decrease from baseline in vasomotor flushes (P less than .01). No effect on total cholesterol or its subfractions, renin substrate, or aldosterone was found. Serum E2 levels fell by 50% in 24 hours after patch removal. Endometrial histology and vaginal cytology showed an estrogen effect.

Administration, Cutaneous↗
PubMed1987

Muscle acetylcholine receptor biosynthesis. Regulation by transcript availability.

The expression of the muscle nicotinic acetylcholine receptor (AChR) on the cell surface entails a complex biosynthetic pathway, involving the expression and assembly of four subunits. The amount of AChR on the cell surface changes throughout muscle development and upon muscle denervation. We have examined the regulatory role of transcript levels on surface AChR expression by RNA blot analysis. During myogenesis of the fusing mouse muscle cell line C2, which expresses an embryonic type of receptor, changes in the rate of appearance of cell surface AChR have been assayed by 125I-alpha-bungarotoxin binding. The maximal increase in the rate of appearance of cell surface AChR occurs upon cell fusion, closely following the maximal increase in transcript levels for the alpha-, beta-, gamma-, and delta-AChR subunits. AChR alpha-, beta-, gamma-, and delta-subunit gene transcript levels have also been examined in innervated and denervated rat and mouse muscle. Muscle denervation results in an increase of transcripts for all four subunits. However, the amount of beta-subunit transcript in innervated rat skeletal muscle is high relative to the other subunit transcripts, and increases less than the other subunit transcripts upon denervation. Our results indicate that, during myogenesis and upon denervation, the availability of AChR subunit transcripts for translation plays a regulatory role in surface AChR appearance.

Animals↗
PubMed1987

Discriminative stimulus properties of oxazepam in the pigeon.

Five pigeons were trained to discriminate IM injections of oxazepam (4.0 mg/kg) from vehicle with responding maintained under a fixed-ratio 30 schedule of food delivery. Under test conditions, responding increased in a dose-dependent manner in all pigeons after the administration of other benzodiazepines including diazepam (0.01-1.0 mg/kg), temazepam (0.01-3.0 mg/kg), halazepam (0.1-56.0 mg/kg), and midazolam (0.1-1.0 mg/kg) as well as the barbiturate pentobarbital (2.0-8.0 mg/kg) and the non-benzodiazepine anxiolytic CL 218,872 (1.0-8.0 mg/kg). At the higher doses of each of these compounds, over 80% of responding occurred on the oxazepam-appropriate key. Cocaine (0.5-4.0 mg/kg), bupropion (3.0-56.0 mg/kg) and nortriptyline (3.0-56.0 mg/kg) failed to substitute for oxazepam even at doses that decreased rates of responding. The discriminative stimulus (DS) effects of the lowest doses of oxazepam and CL 218,872 that produced 100% drug-appropriate responding were blocked by the benzodiazepine antagonist Ro 15-1788. This antagonism was reversed by increasing the dose of the agonists. The DS effects of diazepam were antagonized partially by Ro 15-1788 (3 of 5 pigeons), and the antagonism was reversed by higher doses of diazepam in two of these pigeons. The DS effects of pentobarbital were antagonized by Ro 15-1788 in 2 of 5 pigeons, but the blockade was not reversed by higher pentobarbital doses.

Animals↗
PubMed1987

Epidermal growth factor receptors in lung tumours.

Immunocytochemical analysis of epidermal growth factor (EGF) receptor expression was carried out on frozen sections of 109 primary lung tumours resected at the Brompton Hospital from February 1984 to May 1985. Tumours with detectable levels of this proto-oncogene protein were significantly more frequent among squamous cell carcinomas than among other types of lung tumour. No truncated EGF receptors were detected in the tumours using two monoclonal antibodies (Mabs) directed against different portions of the receptor (EGFR1 and F4). Mab F4 is the first antibody to the EGF receptor to show reactivity in paraffin sections. Southern blot analysis of a subset of the tumours detected amplification of the EGF receptor gene in squamous cell carcinomas but not in adenocarcinomas. The one carcinosarcoma examined had a re-arranged and amplified EGF receptor gene. Measurement of EGF receptor expression in lung tumours can be of diagnostic value and may prove to be useful in the development of antibody-directed therapy.

Adenocarcinoma↗
PubMed1987

Dielectric measurements for the design of an electromagnetic rewarming system.

The work described in this paper is intended to provide a basis for the design of a controlled rewarming system for cryopreserved tissues and organs using electromagnetic energy. For rapid rewarming (say, greater than 10 degrees C/min), the temperature distribution in the organ is effectively determined by the uniformity (or otherwise) of the power deposition, which is in turn controlled by the electrical properties of the perfused tissue. In this contribution, we describe the measurement system we have used to characterize the electrical properties of perfusates and perfused rabbit kidney tissue from -30 to +20 degrees C. Measurements have been made on three perfusates using an open-ended coaxial probe sensor over a continuous range of radio and microwave frequencies covering 50 MHz to 2.6 GHz. Results show that the behavior of the electrical properties with increasing temperature is unfavorable at either end of the frequency range investigated--either the power absorption has a positive temperature coefficient or the penetration depth is too shallow. However, there is a compromise frequency range, determined in part by the perfusate composition, where these factors are much less serious. In this frequency range, the electrical properties of the perfused tissue are dominated by the properties of the perfusate. Modifications to the perfusate composition, e.g., reducing the concentration of electrolytes by adding sucrose, can further improve the temperature dependence of the electrical properties.

Animals↗
PubMed1987

The clinical laboratory evaluation of cryptococcal infections in the acquired immunodeficiency syndrome.

The medical and laboratory records were reviewed in 37 acquired immunodeficiency syndrome (AIDS) patients with cryptococcal infections. In 24 patients with the presentation of cryptococcal meningitis, the initial cerebrospinal fluid (CSF) culture was positive. The initial India ink mount demonstrated organisms in 79% of culture positive CSF specimens. After therapy the subsequent India ink mounts demonstrated 84% sensitivity and 53% specificity with respect to culture outcome. Cultures of blood, bronchoalveolar lavage fluid, and brain were more likely to be positive than cultures from other sites. The initial blood cultures were positive in eight of eight patients at presentation of cryptococcal meningitis. When the initial CSF titer was greater than 1:2, the corresponding CSF culture was always positive. A negative culture during therapy did not necessarily indicate eradication of infection. The initial cerebrospinal fluid and serum cryptococcal antigen titers varied significantly and could not be correlated with survival. In three instances when the CSF cryptococcal antigen titers and cultures were negative, a positive serum cryptococcal antigen greater than 1:8 suggested disseminated infection.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Cryptococcal cellulitis in renal transplant recipients.

We report three cases of cryptococcal cellulitis in renal transplant recipients and review five other cases in the literature. Seven cases of cryptococcal cellulitis occurring in other immunocompromised states are also reviewed and compared with the renal transplant group. Cryptococcal cellulitis in renal transplant recipients affects the skin of the extremities and is seen along with erythema, induration, tenderness, and superficial ulcerations of varying extent. Histopathologic examination shows either a variable lymphohistiocytic infiltration of the reticular dermis and subcutaneous fat or an acute panniculitis. Organisms may be difficult to find on routine sections, and special stains are recommended. Culture of tissue aspirate is an excellent method of diagnosis.

Adult↗
PubMed1987

Antibody responses to hemodialysis-related antigens in chronic hemodialysis patients.

Allergic-type reactions during hemodialysis are sometimes due to sensitization to ethylene oxide. To examine the possibility that additional antigens might be a basis for unexplained reactions, antibodies to formaldehyde and phthalate-related antigens and to dialyzer extracts were measured. Unselected sera from 113 chronic hemodialysis patients (CHP) and 200 control subjects were tested for IgG antibodies to formaldehyde-treated human serum albumin (HSA). The IgG antibody activity was confirmed in sera of five CHP who had used formaldehyde-treated dialyzers. These antibodies also reacted with formaldehyde-treated red blood cells. Sera from 71 CHP and 80 controls were tested for IgE antibodies to diethylphthalate-treated HSA; antibody was detected in two CHP sera. With extracts from hollow-fiber dialyzers, IgG antibody was detected in approximately 1/3 and IgM antibodies in approximately 1/2 of CHP sera. This antibody was found in comparable numbers of control sera. It was concluded that these additional substances are immunogenic and could be involved in allergic-type reactions.

Anaphylaxis↗
PubMed1987

Gastroesophageal reflux in children. Clinical profile, course and outcome with active therapy in 126 cases.

A clinical profile and the course and outcome with therapy of 126 infants and children with gastroesophageal reflux (GER), diagnosed at a median age of 2.5 months and followed for 1.5 to 3.5 years is presented. Features included repeated regurgitation or rumination (99%), signs suggesting esophageal pain (49%, excessive crying "colic," sleep disturbance, Sutcliffe-Sandifer syndrome, respiratory symptoms 42%), failure to thrive (18%), and minor hematemesis (18%). Feeding problems and maternal distress were common, associated with child abuse in four cases. Therapy was initially conservative (posture, thickening of feeds, antacids, bethanechol), augmented by cimetidine in those with proven esophagitis (n = 34, 0.27%). Most (81%) were symptom-free by 18 months of age (55% by 10 months of age); 17 percent had fundoplication with good results; 2 percent have persisting symptoms beyond 2 years of age (1% failed surgery). No deaths were recorded. Surgery was performed for recurrent apneas/aspiration (6%), refractory esophagitis or stricture (5%), and failed medical management (7%). Esophagitis was a significant determinant to outcome, and the importance of selective early endoscopy is emphasized. GER is a cause of considerable morbidity in infants but, with active therapy, is self-limiting in the majority. Certain distinctive clinical signs indicate those patients who require detailed investigation and to whom more aggressive therapeutic efforts should be directed.

Child↗
PubMed1986

Polyethylene glycol-modified ragweed extract: comparison of two treatment regimens.

Fifty ragweed-sensitive subjects were each administered a course of 12 injections of polyethylene glycol-modified ragweed extract. To investigate the effect of two treatment regimens, subjects were paired according to their skin sensitivity to ragweed extract and the severity of their rhinoconjunctivitis the previous year. One of each pair was randomly allocated to receive injections at weekly intervals, and the other subject was to receive injections daily until a local or systemic adverse reaction occurred and then to switch to a weekly schedule for the rest of the course. Blood was obtained immediately before each injection and at the end of the study to examine the rates of change of ragweed-specific IgE and IgG antibody levels and to evaluate whether these or other variables could be used to predict the occurrence of adverse reactions. Immediate reactions were minimal in both groups, but more late reactions occurred in subjects receiving the modified rush regimen; therefore, although the total number of injections received by the two groups was similar, the total dose of protein injected in the rush group was only half that achieved in the weekly group. Treatment induced increases in ragweed-specific IgE and IgG antibodies in both groups; the increase in IgE was similar in the two groups, but the increase in IgG was higher in the weekly group. There was a marked decrease in skin sensitivity to ragweed extract after treatment that was directly related to the IgG antibody response, and therefore, these changes were greater in the weekly group.(ABSTRACT TRUNCATED AT 250 WORDS)

Allergens↗
PubMed1986

Case report: Erdheim-Chester disease: polyostotic sclerosing histiocytosis.

Erdheim-Chester disease is characterised by diffuse metaphyseal and diaphyseal sclerosis of long tubular bones of the appendicular skeleton. In addition, there is an inconstant tendency to visceral involvement by lipo-granulomatous infiltration. Histologically, this condition has marked similarities to Hand-Schuller-Christian disease. A further case is presented which supports the view that Erdheim-Chester disease is part of the spectrum of histiocytoses and not a distinct pathological entity. Polyostotic sclerosing histiocytosis would be an appropriate alternative label for this condition.

Adult↗
PubMed1986

The pathology of pulmonary cryptococcal infections in the acquired immunodeficiency syndrome.

Specimens from premortem pulmonary cytology, transbronchial biopsy, and autopsy were studied in 11 patients with acquired immunodeficiency syndrome who developed pulmonary cryptococcal disease. Nine of 11 patients had culture-proved cryptococcal meningitis. Extremely low T-cell helper/suppressor ratios (mean, 0.12) were observed in seven of 11 patients. In six of eight patients, transbronchial biopsy specimens showed a characteristic interstitial pattern with yeasts in the alveolar septae, minimal cellular inflammation, and no well-formed granulomas. On cytologic examination, organisms were present in seven (100%) of seven cell blocks and five (83%) of six smears prepared from the bronchoalveolar lavage, and in five (63%) of eight bronchial brushings. Small, poorly encapsulated yeast forms were sometimes present, requiring mucicarmine and acid mucopolysaccharide stains for confirmation of the diagnosis of pulmonary cryptococcosis. Overall, bronchoscopy yielded a diagnosis in seven of eight patients. At autopsy, two of five patients demonstrated an interstitial pattern of infection in all lobes of the lung with marked pleural thickening and giant-cell formation; two other patients showed mixed interstitial and intra-alveolar cryptococcal infiltrates. Nodal and disseminated infection were present in four patients. In patients with acquired immunodeficiency syndrome who have cryptococcal meningitis, pulmonary cryptococcal disease is common and must be distinguished from other opportunistic infections.

Acquired Immunodeficiency Syndrome↗