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Biomedical subjects

A Smith

Publications and source records attributed to A Smith.

At least 1,153 records · Page 64Linked to original sources
PubMed1984

Temporal relationships between hormonal concentrations and the electrical resistance of the vaginal tract of blue foxes (Alopex lagopus) at pro-oestrus and oestrus.

During pro-oestrus, baseline LH concentrations for 9 vixens (pooled data) ranged from 0.8 to 5.3 ng/ml. In each vixen, baseline levels were interrupted by elevations of LH ranging from 3.1 to 10.4 ng/ml. A major preovulatory LH surge was detected in all the vixens. The LH peak ranged from 13.5 to 73.0 ng/ml with an average of 27.8 +/- 18.8 (s.d.) ng/ml. Plasma LH concentrations declined to a basal level of 1.3 +/- 1.0 ng/ml within 48 h of the peak value. The duration of the LH surge was 1-3 days. The LH peak occurred 1 or 2 days before any sexual receptivity was observed. All the vixens were mated twice 2-5 days after the LH peak; 8 conceived. Plasma concentrations of oestradiol-17 beta increased gradually during the last 6-7 days before oestrus and reached maximum values (124-373 pg/ml) at the time of the preovulatory LH peak. The first significant increase in plasma progesterone concentration occurred simultaneously with the LH peak. During oestrus (normally 3-5 days), progesterone levels rose steeply, attaining a mean concentration of 57.0 +/- 17.5 ng/ml when the vixens went out of heat. Androstenedione and testosterone values changed similarly, both increasing at the beginning of pro-oestrus and reaching maximum values (805-1879 pg/ml and 328-501 pg/ml respectively) 1 day before to 1 day after the oestradiol-17 beta peak. The electrical resistance of the vaginal tract increased rapidly during the last 2-3 days of pro-oestrus, reaching a maximum value (300-640 omega) approximately 2 days after the oestradiol-17 beta peak that corresponded with the onset of sexual receptivity. Towards the end of oestrus, the values fell to 100-200 omega.

Androstenedione↗
PubMed1984

Enhanced natural killer sensitivity with concomitant clonal selection for cells bearing homogeneously staining regions in the human melanoma cell line MeWo upon induction of differentiation with theophylline.

Culture of the human melanoma cell line MeWo in the presence of 1 mM theophylline was associated with an increase in susceptibility to natural killer (NK)-mediated cytolysis. The phenomenon was detected as early as 72 hours after initiation of theophylline treatment, reaching maximum values at 3-4 weeks and remaining stable for longer than 3 months of testing, provided the cells were maintained in the presence of theophylline. The alteration in target sensitivity was selective for NK-mediated cytolysis, since other mechanisms of cell-mediated cytolysis, including antibody-dependent cell-mediated cytotoxicity and monocyte-mediated and lectin-induced cytolysis, were comparable between untreated and treated cells. The enhanced susceptibility of theophylline-treated cultures to NK lysis, as compared to NK lysis susceptibility of untreated MeWo cells, was not significantly changed by pretreatment of effector lymphocytes with interferon. Evidence for differentiation in theophylline-treated cultures was obtained. In addition, however, cytofluorometric and karyologic analysis revealed the existence of two subpopulations of differing ploidy in the MeWo line. The hypodiploid, NK-sensitive subpopulation, bearing homogeneously staining regions on two chromosomes, could be selected by growth in theophylline. Therefore, selection of subpopulations in heterogeneous tumor cell lines by chemical inducers suggests an alternative and novel mechanism for enhancement of NK sensitivity.

Cell Cycle↗
PubMed1983

Stability of human lymphocyte differentiation antigens when stored at room temperature.

The development of monoclonal antibodies to human differentiation antigens and cytofluorographs have added a new dimension to immune monitoring. However, the technology is such that regionalization will most likely occur. We have demonstrated that human lymphocyte antigens OKT3, OKT4, OKT8 and OKT11 are stable in blood samples stored in ACD at room temperature for less than 72 h. This will allow samples to be analyzed in regional centers.

Antibodies, Monoclonal↗
PubMed1983

Double-inlet left ventricle with rudimentary right ventricle and ventriculoarterial concordance.

Seven hearts were studied that had in common the segmental combination of double-inlet left ventricle, rudimetary right ventricle and ventriculoarterial concordance. The prototype of these hearts has been described as the "Holmes heart" or "single ventricle type A1." Five of the hearts had 2 atrio-ventricular valves; in 1 of these the right valve was minimally straddling. The other 2 had a common valve. In 6 of the hearts the rudimentary right ventricle was obliquely situated on the anterior surface of the dominant left ventricle. The trabecular component was anterior and right-sided with the outlet components and pulmonary trunk in left-sided position. In the final case, both trabecular and outlet components of the rudimentary right ventricle were left-sided. Conduction tissue studies were performed in 2 hearts. In 1, the connecting atrioventricular node and bundle were in anomalous anterolateral position, as expected in double-inlet left ventricle. In the other, a ring-like, posterior, nonbranching bundle connected the regular node in the atrial septum to the branching bundle positioned on the anterior interventricular septum. The anatomic findings are related to the likely modes of presentation and differential diagnosis while the conduction tissue findings are discussed in the light of options for surgical repair. Thus, the term "single ventricle" is best avoided when describing hearts that unequivocally possess 2 ventricular chambers.

Heart Conduction System↗
PubMed1983

Haematoporphyrin and OO'-diacetylhaematoporphyrin binding by serum and cellular proteins. Implications for the clearance of these photochemotherapeutic agents by cells.

Haematoporphyrin derivative (HpD), a mixture of porphyrins, is currently used as a photochemotherapeutic agent in the treatment of neoplasias. The interaction of purified components of HpD with serum and cellular proteins was investigated using absorption and fluorescence spectroscopy. The interactions of haematoporphyrin and OO'-diacetylhaematoporphyrin with human albumin and with haemopexin, the two major serum porphyrin-binding proteins, show stoichiometries of 1 mol of porphyrin bound per mol of protein. The apparent dissociation constants, Kd, are in the range of 1-2 microM for albumin and 3-4 microM for haemopexin. These two major components of HpD would, after intravenous injection, bind to albumin and circulate in serum as albumin complexes. Free porphyrin rather than porphyrin bound to albumin interacts with Morris hepatoma tissue culture cells. A rapid high-affinity saturable transport system operates at free porphyrin concentrations of less than 2 microM. In addition, fluorescence spectra show that components in rat liver cytosol can bind haematoporphyrin and OO'-diacetylhaematoporphyrin and distinguish these binders from those present in rat serum.

Animals↗
PubMed1983

The effect of isotonic amino acid infusions on serum proteins and muscle breakdown following surgery.

Twenty patients undergoing major surgical procedures received constant infusion (21/day) of either 3.5 per cent amino acid (AA) or 5 per cent dextrose (D5W) solutions in addition to other fluid requirements for 4 postoperative days. Ketosis was evident in AA patients as a mean daily beta-hydroxy butyrate excretion of 2.16 +/- 1.39 mmol and respiratory quotient of 0.708 +/- 0.013 compared with 0.28 +/- 0.45 mmol/day and 0.754 +/- 0.015 respectively in the D5W group. The serum total protein and albumin concentrations (but not those of transferrin and prealbumin) were significantly higher in the AA than the D5W group on day 4. However, the mean fluid balance for days 3 and 4 was significantly less positive in AA patients. The mean daily nitrogen balance of -6.6 +/- 7.7 gN/day in AA patients and -9.5 +/- 5.8 gN/day in D5W patients was not significantly different. Mean daily 3-methyl histidine excretion (38.2 +/- 12.3 mumol/mmol creatinine) in AA patients was significantly higher than in D5W patients (31.2 +/- 10.8 mumol/mmol creatinine). With no improvement in nitrogen balance, an increase in muscle protein breakdown and the possibility that decreased fluid retention explains the higher serum total protein and albumin levels, this study fails to demonstrate improved protein sparing by isotonic amino acid infusions following surgery.

Adult↗
PubMed1983

Blood clearance of radioactively labelled cis-diammine 1,1-cyclobutane dicarboxylate platinum (II) (CBDCA) in cancer patients.

The blood and urinary clearances of cis-diammine 1,1-cyclobutane dicarboxylate platinum(II) (CBDCA, JM8) were determined in four patients with malignancy. A 40 muCi iv injection of 191 Pt/193 Pt (3:1)-labelled CBDCA was followed by serial blood and urine sampling to 72 h. The blood clearance was triphasic, mean values for the fast, intermediate, and slow phases being 10.8 min, 2.5 h, and 125 h, respectively. The fraction of activity excreted in the urine within the first 6 h had a mean value of 66.7%, contrasting with 26.4% for cisplatin. There was only a small fraction of CBDCA excreted by the slow phase (1.5%) as against an average of 20% for CHIP and 27% for cisplatin. The early and rapid renal clearance of CBDCA may account for reduced nephrotoxicity.

Antineoplastic Agents↗
PubMed1983

Pancreatic polypeptide secretion. A marker for disturbed pancreatic function in cystic fibrosis.

Pancreatic polypeptide, a 36-amino peptide, is released from the pancreas by a variety of stimuli, including intravenous Boots secretin. Studies in a generalized destructive and inflammatory process such as chronic pancreatitis have revealed a markedly diminished response to stimulation. To assess whether pancreatic polypeptide release in response to Boots secretin provides a useful measure of pancreatic destruction in cystic fibrosis, 41 patients with proven cystic fibrosis, aged 14 months-23 years, and seven control subjects, aged 18-24 years were studied. Serum pancreatic polypeptide, measured by radioimmunoassay, rose from a basal of 18.5 +/- 2.7 pmol/liter to a peak of 35.6 +/- 4.3 pmol/liter at 5 min in cystic fibrosis, and from a basal of 10.8 +/- 2.8 pmol/liter to a 5-min peak of 109 +/- 27.7 pmol/liter in control subjects. The basal levels of both groups were similar but the cystic fibrosis patients had a significantly lower peak response than controls (P less than 0.05). The peak over basal pancreatic polypeptide ratio was calculated and was less than five in 93% of cystic fibrosis patients, whereas all control subjects had a ratio greater than five. Pancreatic polypeptide measurements in response to secretin may be a convenient and useful means of following the course of pancreatic disease in a chronic illness such as cystic fibrosis.

Adolescent↗