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Biomedical subjects

D Harvey

Publications and source records attributed to D Harvey.

At least 91 records · Page 5Linked to original sources
PubMed1990

A high performance liquid chromatography system for the simultaneous assay of some antibiotics commonly found in combination in clinical samples.

Using a single reversed-phase HPLC column with a mobile phase of methanol and 100 mM phosphate buffer, concentrations of seven antibiotics (chloramphenicol, metronidazole, cefuroxime, cephalexin, ceftazidime, ampicillin and benzylpenicillin) which are commonly used clinically in combinations of two or more, can be assayed and results reported within one hour. No endogenous interference was detected in serum, urine or cerebrospinal fluid. The method was highly specific even in the presence of other drugs and metabolites commonly found in clinical samples and provides a rapid, simple technique suitable for use in routine microbiological practice.

Anti-Bacterial Agents↗
PubMed1989

Disparity of amniotic fluid volume and fetal size: problem of the stuck twin--US studies.

The "stuck twin" phenomenon in monochorionic diamniotic (MCDA) pregnancies is characterized by marked disparity in both fluid volume and fetal size between the twin gestations. To determine the prevalence, sonographic characteristics, and clinical outcome of this phenomenon, discharge summaries, placental pathologic reports, and prenatal sonograms from 307 twin pregnancies were reviewed. Of 52 cases of MCDA pregnancies, 18 (35%) demonstrated marked disparity in amniotic fluid volume. In 16 of these 18 cases there was discordant twin growth, further suggesting the diagnosis of twin transfusion syndrome. All 16 cases and an additional nine cases supplied by another center demonstrated a small, morphologically normal fetus in an oligohydramniotic sac suspended anteriorly (72%) or laterally (28%) in the uterus. The amniotic membrane separating this twin from the larger twin in the polyhydramniotic sac was thin, closely applied to the smaller fetus, and difficult to detect. Perinatal morbidity was 100% for all twin pairs, and premature labor occurred in all cases. Perinatal mortality ranged from 88% for the larger/poly twin to 96% for the small/oligo twin.

Adult↗
PubMed1989

Failure to maintain luteal function: a possible cause of early embryonic loss in a cow.

The effect of early pregnancy failure on the release of prostaglandin F2 alpha (PGF2 alpha) in response to oxytocin (Ot) was examined in an abnormal breeder (AB) heifer that was not able to maintain a pregnancy beyond 21 days. This animal was used in three experiments: 1) She received one intravenous injection of 100 IU Ot 17 days after the onset of oestrus (Day 0). Frequent blood samples were taken for the measurement of 15-keto-13,14-dihydro-PGF2 alpha (PGFM) by radioimmunoassay. Daily samples for progesterone (P4) determinations were taken to monitor luteal function. This was then repeated using the same animal at either day 17 or 18 or 19 (day 17-19) of pregnancy. 2) Embryos from superovulated normal breeder (NB) donors were transferred at day 7 to the AB heifer as well as to NB control animals. 3) Seven day old embryos from the superovulated AB heifer were transferred to NB recipient animals. At day 17-19 of pregnancy all the recipient heifers (experiments 2 and 3) were subjected to the same protocol as in experiment 1. The results showed that the ability of Ot to stimulate PGF2 alpha release was reduced in the NB recipients bearing viable embryos when compared to cyclic animals. However, for the AB heifer, Ot stimulated PGF2 alpha release to the same extent whether the animal was cyclic or pregnant. Furthermore, the AB animal did not have the extended luteal function associated with removal of viable embryos on day 17-19. The data suggest that the embryonic loss might have been caused by failure of the embryos to prevent the luteolytic release of PGF2 alpha.

Abortion, Veterinary↗
PubMed1988

Angiotensin influences on tubuloglomerular feedback mechanism in hypertensive rats.

The tubuloglomerular feedback (TGF) mechanism was evaluated in the nonclipped kidney of Goldblatt hypertensive rats from both stop flow pressure (SFP) and single nephron glomerular filtration rate (SNGFR) responses to step increases in late proximal perfusion rate from 0 to 40 nl/min. During control conditions, increases in late proximal perfusion rate produced flow dependent decreases in SFP and SNGFR with maximal values of 10.2 +/- 1.0 mm Hg and 12.9 +/- 2.5 nl/min, values similar to those obtained in normal rats. During ACE inhibition (MK 422; 0.6 mg/kg/hr), arterial pressure decreased from 168 +/- 8 to 137 +/- 7 mm Hg and there was a marked attenuation in the magnitude of SFP feedback responses (delta = 2.5 +/- 0.3 mm Hg). SNGFR feedback responses, however, were not significantly impaired. Direct decreases in renal arterial pressure reduced control SFP but SFP feedback responses were maintained, indicating that the attenuated SFP feedback responses during ACE inhibition were not due to decreased arterial pressure. Superimposed infusion of angiotensin II during ACE inhibition partially restored SFP feedback responses. In contrast, norepinephrine infusion did not result in a similar restoration of SFP feedback sensitivity. These results indicate that the nonclipped kidney of Goldblatt hypertensive rats has an intact TGF mechanism as assessed from SFP and SNGFR feedback responses. Furthermore, ACE inhibition attenuates SFP but not SNGFR feedback responses, and systemic angiotensin II infusions can restore SFP feedback responsiveness towards normal.

Angiotensin II↗
PubMed1988

Sonography of the postoperative shoulder.

Fifty-three patients with 60 symptomatic shoulders underwent shoulder sonography for recurrent postoperative symptoms after either acromioplasty (10 shoulders) or repair of a full-thickness rotator cuff tear in addition to acromioplasty (50 shoulders). Because surgery distorts landmarks, an understanding of the surgical procedures and their characteristic sonographic appearances is essential. After acromioplasty, the characteristic sharp margination or the acromion was replaced by a less distinct, irregular surface. After repair of a cuff tear, characteristic sonographic appearances included visualization of a reimplantation trough and loss of the echogenic subdeltoid bursa. When the cuff was intact after surgery, echogenicity was abnormal in all cases (17 shoulders). Sonography accurately diagnosed recurrent cuff tears in all 26 shoulders in which surgical proof was available and confirmed an intact cuff in 10 of 11 cases. In one shoulder, a cuff hematoma was incorrectly interpreted as a full-thickness tear. These findings suggest that sonography is an effective procedure for evaluating a postoperative patient with recurrent shoulder symptoms.

Acromion↗
PubMed1988

Value of the yolk sac in evaluating early pregnancies.

To determine the potential value in identifying a yolk sac in women with suspected ectopic pregnancies, 211 consecutive women who were referred to pelvic sonography with this clinical indication were prospectively studied. Of the 211 patients examined, 104 proved to have a normal intrauterine pregnancy (IUP), 59 had an abnormal (nonviable) IUP, and 48 had a surgically-proven ectopic pregnancy. Considering only intrauterine "sacs" that lacked a visible embryo, a yolk sack was identified in 16 of 26 (62%) normal IUPs, and 3 of 19 (16%) abnormal IUPs, but was not seen in any of six pseudo-gestational sacs in women with ectopic pregnancies. In comparison, a double decidual sac (DDS) finding was thought to be present in 24 of 26 (92%) normal gestational sacs, 12 of 19 (63%) abnormal gestational sacs, and 2 of 6 (33%) pseudogestational sacs. We conclude that in women in whom a living embryo is not identified, demonstration of a yolk sac is reliable evidence for early IUP, and virtually excludes the possibility of an ectopic gestation. Although a yolk sac is less frequently observed than a DDS finding, it is also more specific evidence for an IUP. Careful attention to the yolk sac should permit earlier, more reliable diagnoses of IUP than previously possible.

Female↗
PubMed1988

Antibiotic therapy of the newborn.

The bacteria infecting newborn babies have changed over the last few decades and vary from place to place. Each neonatal unit must therefore make its own choice of antibiotics to attack the local pathogens. This choice must be reconsidered regularly because of the continuing change in pathogens, such as the recent problems encountered with Staphylococcus epidermidis. The newer beta-lactam antibiotics, especially the third-generation cephalosporins, are proving useful in the treatment of neonatal infections.

Anti-Bacterial Agents↗
PubMed1986

Behavioural differences of school-age children who were small-for-dates babies.

Twenty-one children aged between five and nine years who were small for gestational age (SFD) at birth and whose intra-uterine head growth was shown by ultrasonography to be slowing before 35 weeks were observed in a special room, using video-cameras. Their behaviour was compared with that of 21 matched control children who had had normal birthweight. The children in the SFD group were quieter, more compliant and less active than the control group, and their play behaviour suggested that they were less advanced developmentally. The behaviour of the mothers of the SFD group showed that they were aware of their child's problems and tried to compensate for it by teaching the child while they were waiting for the observational session to start, by sitting closer to the child during a drawing test, and by using more words to explain it.

Body Height↗
PubMed1986

Influence of serum Ca concentration on circulating molecular forms of PTH in three species.

The influence of serum calcium concentration on total circulating parathyroid hormone (PTH) and on the relative amount of intact PTH-(1-84) and large carboxyterminal fragments was studied in the canine and bovine species and in man. Serum calcium was modified through infusions of CaCl2 or EDTA and samples obtained in time for the measurement of serum calcium and PTH concentrations. Pools of serum, corresponding to specific serum calcium concentrations, were analyzed by gel chromatography in all species. PTH was measured with a carboxyterminal radioimmunoassay. In basal conditions, total serum PTH was composed mostly of large carboxyterminal fragments, intact PTH-(1-84) representing less than 25% of the hormone in any species. With hypercalcemia, (greater than or equal to 2.0 mg/dl), total serum PTH decreased only to 40% of the original value measured in all species, despite serum calcium concentrations of over 13 mg/dl. The relative amount of intact PTH-(1-84) remained unchanged in the bovine and canine species and slightly decreased in man. Hypocalcemia (less than or equal to 2.0 mg/dl) induced a 300-450% increase in the basal PTH value measured. The relative amount of intact PTH-(1-84) became as or more important than carboxyterminal fragments in the canine species and in man, respectively, and remained slightly less in the bovine species. Despite small quantitative variations between species, these results indicate that changes in serum calcium concentration induced acute modification in PTH secretion or PTH peripheral metabolism, altering the ratio of intact hormone to carboxyterminal fragments in circulation.

Adult↗
PubMed1986

Endocytotic activity in the endometrium during conceptus attachment in the cow.

The uptake of horseradish peroxidase tracer injected into the uterine lumen of the cow was studied during the period of conceptus attachment (Days 18-21; Day 0 = oestrus) and also in cyclic animals. Endocytosis occurred in pregnant and non-pregnant cows but was especially marked when circulating progesterone concentrations were high. By 20 min after injection, the tracer was located in apical endocytotic vesicles and in organelles of the lysosomal system. In addition, some of the horseradish peroxidase-containing vesicles were associated with the lateral membranes of the cells and the tracer was also present in the intercellular spaces and beneath the basal membrane, especially in pregnant animals by the time of conceptus attachment. There was no evidence that pinopod-like functions could be attributed to large cytoplasmic protrusions from endometrial cells. Rather, the protrusions seemed to be involved in secretory processes. The presence of clear vesicles among the endocytotic vesicles suggested a coupled secretory-endocytotic activity of the cells, the significance of which remains to be determined.

Animals↗
PubMed1985

Strategies for the treatment of bacterial infections in the newborn.

Antibiotics are widely used in the treatment of premature low birth-weight babies, either as blind therapy before infection is confirmed or, more specifically against a pathogen of known antibiotic susceptibility. The requirements of an antibiotic for use in the newborn are different from those in older patients and in almost every respect there are differences in the pharmacology and pharmacokinetics of antibiotics in the very young. A wide range of bacteria are responsible for infection in the new born and the distribution of these organisms will vary not only from country to country, but also from hospital to hospital. Antibiotics in current use are less effective against bacteria infecting the newborn than they once were and the introduction of new antibiotics, notably the third generation cephalosporins, provides an opportunity to reassess current antibiotic practices. This paper outlines the general considerations for chemotherapy in small babies and attempts to identify those areas where a review of current antibiotic practice is required. It is essential that decisions regarding antibiotic policies for neonatal units should be made locally and that they reflect local experience and the range of pathogens most frequently encountered and their sensitivity patterns.

Aminoglycosides↗
PubMed1984

Identification of 17 beta-estradiol as the estrogenic substance in Saccharomyces cerevisiae.

Saccharomyces cerevisiae possesses a high-affinity estrogen binding protein and an endogenous ligand that displaces [3H]estradiol from both the yeast binding protein and mammalian estrogen receptors. Semipurified preparations of this ligand have been shown to exhibit estrogenic activity in mammalian systems. We now describe the purification procedure and ultimate identification of the estrogenic substance in extracts of S. cerevisiae as 17 beta-estradiol. Organic solvent extracts of commercially obtained dried yeast were sequentially chromatographed on silica gel columns and then subjected to a series of reversed phase HPLC fractionations. Active ligand was monitored by [3H]estradiol displacement in a rat uterine cytosol assay. After seven chromatography steps, the purified and highly active ligand exhibited a single peak with retention times identical to those of 17 beta-estradiol on both HPLC and GC. The yeast material was identified as 17 beta-estradiol by its UV absorbance and mass spectrometric fragmentation pattern. In addition, radioimmunoassay confirmed the presence of approximately the same mass of 17 beta-estradiol (approximately equal to 800 ng/1.5 kg of yeast) as estimated both by a competitive binding assay with estrogen receptor and by mass spectrometry. Extraneous contamination by estradiol was excluded by repeat experiments with different batches of starting material and demonstration of estradiol by RIA in conditioned medium and cell pellets of laboratory-grown S. cerevisiae whereas non-conditioned medium did not possess the steroid. We conclude that 17 beta-estradiol is a yeast product.

Estradiol↗
PubMed1984

Follow-up study of children whose mothers were treated with warfarin during pregnancy.

Twenty-two children whose mothers took the oral coumarin anticoagulant warfarin during pregnancy were seen, to assess their physical and mental development; a comparison was made with matched controls. No significant difference was observed between the study group and controls, nor within the study group according to the period of gestation when their mothers took warfarin.

Body Height↗
PubMed1984

Fat loss during feeding of human milk.

A rise in the fat concentration of human milk within the syringe was noted towards the end of continuous infusion but not with intermittent bolus gastric feeding. The rise in the former was reduced most simply and effectively by using an eccentric nozzle syringe and tilting the pump up at an angle of between 25 degrees and 40 degrees.

Dietary Fats↗
PubMed1983

Herpes zoster-associated encephalitis: clinicopathologic report of 12 cases and review of the literature.

Herpes-zoster associated encephalitis (HZAE) is an uncommon complication of herpes zoster. Over 8 years, we evaluated 12 patients with this clinical diagnosis. The majority of our patients were elderly, immunosuppressed, and found to have disseminated skin lesions prior to the onset of CNS symptoms. All patients had abnormal EEGs, and CSF pleocytosis was found in most. In the seven patients who were tested, specific antibody to the varicella-zoster membrane antigen (FAMA) was detected in spinal fluid during the course of the illness. Although three patients died during the period of active infection, the virus could not be definitively implicated as the cause of death. These HZAE patients could not be distinguished from our other herpes zoster patients on the basis of age, initially involved dermatome, or mortality rate. However, among herpes zoster patients who survived, duration of hospitalization was significantly longer in those with a diagnosis of HZAE. All surviving HZAE patients had a slow but eventual return to their prior cognitive status.

Adult↗