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Biomedical subjects

A C White

Publications and source records attributed to A C White.

At least 127 records · Page 7Linked to original sources
PubMed1982

Site-selective growth of a hormone-responsive human breast carcinoma in athymic mice.

MCF-7 is a human breast cancer line which requires estradiol supplementation for growth in s.c. tissues of athymic mice. In order to evaluate the influence of host site on hormone-dependent tumorigenicity and growth, MCF-7 cells were inoculated into tissues varying in ability to concentrate exogenous estradiol. Tumorigenicity was defined in terms of latency, threshold inoculum size, and tumor growth and progression. We observed that sites such as lung rarely supported MCF-7 tumors. However, moderately estrophilic sites such as mammary fat and adjacent subcutaneum and dermis supported the growth of small MCF-7 tumors from large tumor cell inocula, but only in estrogenized mice. In contrast, the highly estrophilic sites, brain and periuterine tissues, produced rapidly growing tumors from small tumor cell inocula. Only in periuterine tissues did tumors develop in the absence of exogenous estradiol. These studies demonstrate that tumorigenicity and growth rates of estrogen-dependent MCF-7 tumors vary as a function of tissue implantation site.

Animals↗
PubMed1981

Estrogen induced growth of human breast cancer cells (MCF-7) in athymic nude mice is enhanced by secretions from a transplantable pituitary tumor.

MCF-7, a human breast carcinoma cell line, was maintained s.c. in female athymic nude mice for a period of 5-6 weeks. Administration of estrogen (s.c. pellet of 17 beta-estradiol and estrone in drinking water, 0.5 mg/l) to these mice resulted in sustained (P less than 0.001) growth of MCF-7 tumors. Grafting of a prolactin and growth hormone secreting rat pituitary tumor to the estrogen-treated mice resulted in an increased (P less than 0.05) rate of MCF-7 tumor growth. MCF-7 did not grow in athymic nude mice grafted with rat pituitary tumor alone or in mice without hormone treatment (controls). Thus, secretions of pituitary hormones alone are not capable of promoting in vivo growth of MCF-7 although such secretions significantly enhance estrogen-induced growth of this cell line. A synergism between pituitary hormones and estrogen for in vivo growth of a human breast carcinoma has been demonstrated in this study.

Animals↗
PubMed1981

Plasma substance P levels in normotensive and hypertensive subjects.

Since substance P is a potent natriuretic, diuretic, and vasodilatory peptide, a radioimmunoassay for substance P was developed, and its levels measured in the plasma of normal subjects and patients with essential hypertension. The plasma substance P levels were 186+/-14 pg/ml in normal subjects and 164+/-3 pg/ml in hypertensive patients. When the sodium content of their diet was reduced to 10 mEq/day, substance P levels failed to change, but plasma renin activity and urinary kallikrein increased. An acute saline infusion also failed to alter plasma substance P levels. Assuming an upright posture increased plasma renin activity, but not substance P, in both groups of subjects. Thus, it appears that substance P is not involved in the control of blood pressure, kallikrein excretion or renin release in man.

Diet↗
PubMed1980

Serum and subcutaneous chamber fluid dynamics of penicillins after single large parenteral doses.

Serum and subcutaneous chamber fluid (CF) dynamics of penicillin G, ampicillin, and amoxicillin were studied in rabbits after single large parenteral doses comparable to doses used in treating gonorrhea and endocarditis. The effects of parenteral probenecid and of injection of an antibiotic directly into a subcutaneous chamber ("intrachamber" injection) also were studied. Peak serum antibiotic concentrations exceeded peak CF concentrations and occurred sooner. Antimicrobial activity persisted longer in CF than in serum. Percent penetration [100 x (CF peak/serum peak)] of CF was least after intramuscular ampicillin and amoxicillin, was greatest after intrachamber ampicillin and intramuscular aqueous procaine penicillin G, and was related to duration of antibiotic concentration gradients from serum to CF. Intramuscular aqueous crystalline penicillin G resulted in higher serum and CF penicillin G concentrations than intramuscular aqueous procaine penicillin G, which prolonged the duration of penicillin G in serum and CF. Amoxicillin diffused into CF more readily than ampicillin. Probenecid resulted in higher early serum and CF antibiotic concentrations, but had little or no effect on duration of antibiotic activity. Intrachamber ampicillin resulted in more prolonged serum and CF ampicillin activity than intramuscular ampicillin, but much lower peak serum concentrations. The data suggest a possible means by which probenecid improves the efficacy of gonorrhea therapy with aqueous procaine penicillin G. Intrachamber administration of penicillins could be useful in treating experimental infections requiring prolonged therapy.

Amoxicillin↗
PubMed1980

Radioimmunoassay for Bacteroides fragilis infections.

Radioimmunoassay methods were evaluated for immunoglobulin G and immunoglobulin M antibodies against Bacteroides fragilis antigen. Of 12 serum samples from patients with B fragilis infections, 9 had higher concentrations of immunoglobulin G antibodies than any from 11 control subjects. Of 9 serum samples from infected patients, 6 had higher concentrations of immunoglobulin M than any from control subjects. Six serum samples from patients with Escherichia coli bacteremia did not contain elevated concentrations of immunoglobulin G or immunoglobulin M antibodies against B. fragilis antigen.

Antibodies, Bacterial↗
PubMed1980

Quantitative microhaemagglutination assay for Treponema pallidum antibodies in experimental syphilis.

The quantitative microhaemagglutination assay for Treponema pallidum antibodies (MHA-TP) was studies in 52 untreated and treated rabbits with experimental syphilis. Rabbits with incubating experimental syphilis were cured or inadequately treated with penicillin G and some cured rabbits were later reinfected. MHA-TP conversion occurred within 45 days in untreated rabbits. Titres reached peak levels about four months after inoculation and remained relatively high for up to two years. The quantitative MHA-TP test differentiated between rabbits cured of experimental incubating syphilis and those untreated and inadequately treated. MHA-TP titres decreased after treatment given six or 12 months after inoculation but reversion did not occur. MHA-TP conversion or significant increases in titre occurred as soon as seven days after reinfection and preceded corresponding changes in a quantitative non-treponemal test. The MHA-TP is useful as a screening test for treponemal antibodies in rabbits. The quantitative MHA-TP in humans after treatment for syphilis and reinfection deserves further study.

Animals↗
PubMed1979

Autoanalgesia: acquisition, blockade and relationship to opiate binding.

Acquisition of autoanalgesia (behaviorally activated antinociception) was assessed across 7 consecutive days by shocking rats 10 sec after the determination of their tail-flick latencies. Thus the effect of conditioned fear on antinociception was being investigated, since each shock preceded the subsequent tail-flick test by 24 h. Autoanalgesia was acquired by the second fear-conditioning trial. Although pretreatment with naltrexone or diazepam had no effect, spinal cord transection at the thoracic level effectively obviated autoanalgesia. Investigations of opiate and opioid binding indicated significantly less binding in the fear-conditioned rats as well as an inverse relationship between binding and antinociception. These changes in binding are suggestive of partial mediation of autoanalgesia by an endogenous opiate peptide that is released by the fear-conditioning procedure.

Analgesia↗
PubMed1979

Psychogenic fever: entity or nonentity?

A review of the literature suggests that body temperature may rise when a person is under emotional stress. The term "psychogenic fever" has been applied to this phenomenon. A study of temperature and pulse rate of psychiatric patients diagnosed predominantly as neurotic in a university teaching hospital was undertaken. Changes in pulse rate indicated that the period before ward rounds was more stressful than other times of the day. However, psychogenic fever in these patients was not found. One case of factitious fever was uncovered during the study.

Body Temperature Regulation↗
PubMed1978

Histoplasmosis in immunosuppressed patients.

Infection with Histoplasma capsulatum in 58 patients whose immune responses were suppressed (Immunosuppressed patients) (16 from the present series and 42 described previously) was analyzed. The most common underlying diseases were Hodgkin's disease (29 per cent), chronic lymphocytic leukemia (19 per cent) and acute lymphocytic leukemia (17 per cent). Sixty-three per cent of the patients had received cytotoxic drugs, and 57 per cent had taken corticosteroids. Widely disseminated infection occurred in 88 per cent of the patients, with predominant involvement of lungs and organs of the reticuloendothelial system. Localized pulmonary infection was present in the remaining patients. The most useful diagnostic method was bone marrow biopsy with microscopic examination for the intracellular yeast form of H. capsulatum. Biopsy of oral lesions, lung, liver and lymph node also proved diagnostically helpful. Growth of H. capsulatum in culture was frequently too slow to be beneficial in diagnosing histoplasmosis in ill patients. Serologic methods were of little diagnostic help in this population of immunosuppressed patients. The response to amphotericin B therapy was excellent (6.7 per cent mortality rate) in those patients in whom the diagnosis was established early and in whom a full course of antifungal therapy could be given. In contrast, the mortality rate in patients who received no antifungal therapy or less than 1 g of amphotericin B was 100 per cent.

Adult↗
PubMed1978

Parameters affecting the enzyme-linked immunosorbent assay of immunoglobulin G antibody to a rough mutant of Salmonella minnesota.

An enzyme-linked immunosorbent assay was developed to detect rabbit immunoglobulin G antibodies against purified lipopolysaccharide of the rough Re mutant of Salmonella minnesota. The time necessary for each step was investigated, and this resulted in a test that could be completed in 1 working day. Serial dilutions of rabbit sera drawn throughout immunization with the Re mutant revealed an elimination of the prozone effect upon prolonged immunization. We interpret this to demonstrate an increase in immunoglobulin G affinity for the lipopolysaccharide on prolonged immunization. We propose that the enzyme-linked immunosorbent assay prozone effect be investigated for use as a measure of antibody affinity.

Animals↗
PubMed1978

Problems associated with the analysis and interpretation of saliva lithium.

The correlation between serum and saliva lithium levels in patients undergoing lithium prophylaxis therapy is discussed. Although a high correlation can be obtained, there is an unacceptably high individual variation of paired results. Two strategies were used in an attempt to improve the reliability of saliva as a predictor of serum levels. A naturally occurring marker in saliva and serum was used. This showed high correlation but still did not prevent large sporadic differences. Serially paired results in individual patients also showed occasional excessive variation. Although saliva lithium has been used for monitoring when serum assessment is impracticable, it is considered that it is, as yet, an unreliable technique.

Humans↗
PubMed1978

Aspergillus fumigatus epidural abscess in a renal transplant recipient.

An epidural abscess caused by Aspergillus fumigatus occurred in a recipient of a cadaveric, renal allograft. The patient had persistent back pain and a peripheral neuropathy that involved the lower extremities. Signs of spinal cord compression evolved. No definite portal of entry was found. Diagnosis was made by histologic examination and culture of a biopsy specimen. Therapy, consisting of aggressive surgical debridement, intravenous amphotericin B, and oral flucytosine was unsuccessful in eradicating the organism. At postmortem examination, Aspergillus was identified at the abscess site. To our knowledge, aspergillosis presenting as an epidural abscess in the immunosuppressed, renal transplant recipient has not previously been reported and should be considered in the differential diagnosis of back pain and peripheral neuropathy in such a patient.

Abscess↗