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Biomedical subjects

D W Wilson

Publications and source records attributed to D W Wilson.

At least 19 recordsLinked to original sources
PubMed1992

Soluble N-ethylmaleimide-sensitive fusion attachment proteins (SNAPs) bind to a multi-SNAP receptor complex in Golgi membranes.

Soluble N-ethylmaleimide-sensitive fusion attachment proteins (SNAPs) are required for the binding of N-ethylmaleimide-sensitive fusion protein (NSF) to Golgi membranes and are, therefore, required for intra-Golgi transport. We report the existence of distinct alpha/beta-SNAP and gamma-SNAP-binding sites in Golgi membranes that appear to be part of the same receptor complex. Cross-linking studies with alpha-SNAP demonstrate that an integral membrane protein of between 30-40 kDa is the alpha-SNAP binding component of the multi-SNAP receptor complex. These data suggest that SNAPs function by independently binding to a multi-SNAP membrane-receptor complex, thereby activating them to serve as adaptors for the targeting of NSF.

Amino Acid Sequence↗
PubMed1992

Relationship of proliferating cell nuclear antigen (PCNA) in prostatic carcinomas to various clinical parameters.

Proliferating cell nuclear antigen (PCNA) expression was determined immunohistochemically, using a monoclonal antibody PC10, in 102 prostatic carcinoma samples and in prostate tissue from 21 patients with benign prostatic hyperplasis (BPH). The percentage of cells with stained nuclei ranged from 1% to 58% in the carcinoma specimens and 0% to 10% in the BPH specimens. A semiquantitative scoring system was devised for the degree of PCNA positivity observed in the tumors. Statistical analysis of the PCNA score in relation to the histological grade of the tumors gave a significant positive or negative correlation between these parameters P less than 0.001. No significant correlation between PCNA score was, however, seen with metastatic status, T category (TMN classification) of the primary tumor, or the patient's age at diagnosis. In 65 prostatic cancer patients of known survival, those individuals whose tumors had a PCNA score of +/- (less than 10% of nuclei stained) were compared with those patients whose tumors were either 1+, 2+, or 3+ (greater than 10% of nuclei stained). Life table analysis of the two groups indicated that the patients with the lower PCNA score survived significantly longer than those with the higher PCNA scores, P less than 0.04. Comparison of the Ki-67 expression in frozen sections with the PCNA expression in wax-embedded tissue of 86 prostatic carcinomas was also undertaken. A significant correlation between these two parameters was found, P less than 0.001, although the growth fraction estimated by Ki-67 expression was generally lower than that given by the PCNA scoring system.

Antibodies, Monoclonal↗
PubMed1992

Pathological and clinical associations of Ki-67 defined growth fractions in human prostatic carcinoma.

Estimation of the growth fraction of 153 prostatic carcinoma specimens employing Ki-67 immunostaining was undertaken and its relationship to various clinical parameters investigated. In prostate specimens, the percentage of tumour nuclei expressing Ki-67 antigen was measured and assigned a Ki-67 score. It was observed that high Ki-67 scores were associated with the poorly differentiated tumours, the correlation of this proliferation marker with histological grade was found to be significant (P less than 0.001). No relationship was observed between the Ki-67 score of the primary tumour with either the patient's age or with the primary tumor stage (T category). The metastatic status of the patient at diagnosis and the Ki-67 score of the tumour were correlated (P less than 0.05), higher Ki-67 scores being associated with M1 disease. Life-table analysis of 86 patients who subsequently received androgen withdrawal therapy, was undertaken with reference to the various Ki-67 scores of their primary tumors. A statistically significant difference in survival times was observed in patients whose Ki-67 values were less than 1% (P less than 0.0001) when compared to those patients whose tumours expressed 1% and over Ki-67 positivity, the former having longer survival times. When patients were subdivided according to their metastatic status and similar life-table analyses were carried out, no statistical difference was found between survival times and Ki-67 scores in M0 staged patients. In the M1 population of patients, however, those patients whose tumours were negative for Ki-67 expression had significantly longer survival times than those patients whose tumours exhibited positive Ki-67 staining (P less than 0.01). Comparing M1 staged patients whose prostate tumor cells exhibited less than 1% Ki-67 positive nuclei with M1 staged patients whose prostate tumour cells contained 1% and higher Ki-67 stained nuclei, a significantly longer survival time was found in the former group of patients (P approximately 0.0001).

Adult↗
PubMed1992

Bile acid fractionations by high-performance liquid chromatography in equine liver disease.

Serum bile acids were fractionated by high-performance liquid chromatography (HPLC) in 13 control and 8 cases of liver disease in horses. The severity and type of liver injury was determined by histopathological examination of biopsy and/or necropsy specimens. The total serum bile acids (tSBA) were determined in these horses by an enzymatic method (SBA-EA) and by summation of the bile acids (SBA-LC) as fractionated by the HPLC. The SBA-LC were generally higher than the SBA-EA in both the controls and liver disease and they did not parallel each other. The primary bile acids, total cholates and total chenodeoxycholates accounted for most of the tSBA increases in liver disease. There was a shift in profile from taurocholate to free (unconjugated) cholate in direct relation to the severity of the liver injury. Among the secondary bile acids, total deoxycholates and total taurodeoxycholates increased at random. The pattern of the SBA profile in relation to the severity of the liver disease suggested that hepatocellular excretion is the most sensitive step in the enterohepatic circulation of the bile acids.

Animals↗
PubMed1992

A comparison of menstrual cycle profiles of salivary progesterone in British and Thai adolescent girls.

Menstrual-cycle profiles of salivary progesterone concentration, obtained by radioimmunoassay of daily samples collected throughout the cycle, were obtained from Thai (n = 232) and British (n = 130) adolescent girls up to 4 years postmenarche. These profiles were graded from 1 to 5 ranging, respectively from concentrations at the detection limit of the assay to profiles generally observed for the mature premenopausal woman. Contingency table analysis of the grade frequencies for Thai-British pairs of girls matched for chronological age and age at menarche (n = 2 x 90) demonstrated that British girls had more mature cycles (22/90) than Thais (11/90) (P less than 0.05) particularly in the first 2 years postmenarche (P less than 0.01). For these matched pairs of girls there was no evidence to support the view that girls with an early age of menarche develop their profiles more quickly following menarche than those with a late age of menarche, as previously reported and which was thought to be important in the development of breast cancer. The findings of this study also suggest that adolescent girls in Britain develop their menstrual cycle profiles of salivary progesterone more quickly than their Thai counterparts and this may be of value in formulating hypotheses regarding any role that ovarian progesterone secretion may have on subsequent breast cancer risk.

Adolescent↗
PubMed1992

A multisubunit particle implicated in membrane fusion.

The N-ethylmaleimide sensitive fusion protein (NSF) is required for fusion of lipid bilayers at many locations within eukaryotic cells. Binding of NSF to Golgi membranes is known to require an integral membrane receptor and one or more members of a family of related soluble NSF attachment proteins (alpha-, beta-, and gamma-SNAPs). Here we demonstrate the direct interaction of NSF, SNAPs and an integral membrane component in a detergent solubilized system. We show that NSF only binds to SNAPs in the presence of the integral receptor, resulting in the formation of a multisubunit protein complex with a sedimentation coefficient of 20S. Particle assembly reveals striking differences between members of the SNAP protein family; gamma-SNAP associates with the complex via a binding site distinct from that used by alpha- and beta-SNAPs, which are themselves equivalent, alternative subunits of the particle. Once formed, the 20S particle is subsequently able to disassemble in a process coupled to the hydrolysis of ATP. We suggest how cycles of complex assembly and disassembly could help confer specificity to the generalized NSF-dependent fusion apparatus.

Adenosine Triphosphate↗
PubMed1992

Mechanisms and pathology of monocrotaline pulmonary toxicity.

Monocrotaline (MCT) is an 11-membered macrocyclic pyrrolizidine alkaloid (PA) that causes a pulmonary vascular syndrome in rats characterized by proliferative pulmonary vasculitis, pulmonary hypertension, and cor pulmonale. Current hypotheses of the pathogenesis of MCT-induced pneumotoxicity suggest that MCT is activated to a reactive metabolite(s) in the liver and is then transported by red blood cells (RBCs) to the lung, where it initiates endothelial injury. While several lines of evidence support the requirement of hepatic metabolism for pneumotoxicity, the mechanism and relative importance of RBC transport remain undetermined. The endothelial injury does not appear to be acute cell death but rather a delayed functional alteration that leads to disease of the pulmonary arterial walls by unknown mechanisms. The selectivity of MCT for the lung, as opposed to that of other primarily hepatotoxic PAs, appears likely to be a consequence of the differences in hepatic metabolism and blood kinetics of MCT. A likely candidate for a reactive metabolite of MCT is the dehydrogenation product monocrotaline pyrrole (MCTP). Secondary or phase II metabolism of MCT through glutathione (GSH) conjugation has been characterized recently and appears to represent a detoxification pathway. The role of inflammation in the progression of MCT-induced pulmonary vascular disease is uncertain. Both perivascular inflammation and platelet activation have been proposed as processes contributing to the response of the vascular media. This review presents the experimental evidence supporting these hypotheses and outlines additional questions that arise from them.

Animals↗
PubMed1991

Red blood cells augment transport of reactive metabolites of monocrotaline from liver to lung in isolated and tandem liver and lung preparations.

Monocrotaline (MCT) is a pyrrolizidine alkaloid that causes pulmonary hypertension in rats by mechanisms which remain largely unknown. MCT is thought to be activated in the liver to a reactive intermediate that is transported to the lung where it causes endothelial injury. Our previous pharmacokinetic work demonstrated significant sequestration of radioactivity in red blood cells (RBCs) of rats treated with [14C]MCT. To determine whether this RBC sequestration might be important in the transport of reactive MCT metabolites, we compared the effect of inclusion of RBCs in the perfusion buffer on the extent of covalent binding of [14C]MCT to rat lungs in tandem liver-lung preparations. The potential effect of RBCs in stabilizing reactive intermediates was evaluated by preperfusion of isolated liver preparations with [14C]MCT with and without RBCs, separation and washing of the RBC fraction, and subsequent (90 min later) perfusion of washed RBCs or buffer alone in isolated perfused lungs. Covalent binding to lung tissues was determined by exhaustive methanol/chloroform extractions of unbound label from homogenized lung tissue followed by scintillation counting of residual 14C. Covalent binding was expressed as picomole MCT molecular weight equivalents/mg protein. Comparison of the relative capability of these isolated organ preparations for conversion of MCT to polar metabolites was done by extraction and HPLC analysis of perfusate at the end of the experiment. Isolated livers converted 65-85% of MCT to polar metabolites compared with less than 5% conversion in the isolated lungs. Inclusion of RBCs in the buffer of tandem lung liver preparations perfused with 400 microM [14C]MCT increased the covalent binding to the lung from 97 +/- 25 (buffer alone) to 182 +/- 36 (buffer + RBC) pmol/mg protein. At the end of these perfusions, RBCs contained 1552 +/- 429 pmol/mg hemoglobin of which 333 +/- 98 pmol/mg hemoglobin resisted exhaustive solvent extraction. After 90 min at room temperature, buffer with 400 microM [14C]MCT preperfused in isolated livers resulted in covalent binding to isolated perfused lung of 0.8 +/- 0.4 pmol/mg protein while washed RBCs isolated from buffer of similar liver preperfusions preparations resulted in 53 +/- 7 pmol/mg protein bound to lung. Control groups perfused with 400 microM [14C]MCT in buffer or buffer + RBCs through isolated lungs only resulted in covalent binding of 2 +/- 1 or 1 +/- 0.6 pmol/mg protein respectively. We conclude: (1) RBCs significantly augment the transport of lung reactive MCT metabolites from the liver to the lung.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1991

Pharmacokinetics of intratracheally administered aflatoxin B1.

High concentrations of the carcinogen aflatoxin B1 (AFB1) are commonly found in respirable, airborne grain dusts, and inhaled AFB1 has been shown to be a risk factor for occupational pulmonary carcinogenesis. The fate of AFB1 exposure via the respiratory tract is therefore of interest in an evaluation of potential occupational risk. The pharmacokinetic disposition of intratracheally administered AFB1 was studied in male Sprague-Dawley rats. Blood and tissues were sampled at selected intervals for 3 weeks following administration of a single dose of grain dust-adsorbed or microcrystalline [3H]AFB1 (6 micro-Ci: microgramsg/kg). The blood concentration-time profiles from both groups best approximated a two-compartment open model with first-order absorption. The first-order absorption rate constant was significantly less in the animals given dust-adsorbed AFB1 than in those receiving microcrystalline AFB1 (0.083 vs -0.1060 min -1, respectively), although the first-order elimination rate constants for both groups were nearly identical (0.00928 and 0.00921 hr-1, respectively). Blood concentrations of the AFB1 metabolites AFM1, AFQ1, AFL, and AFP1 showed little differences among the two groups. The tissue concentrations of aflatoxins for the microcrystalline group were significantly greater at 3 hr in all tissues examined except for the trachea and lung in which those for the dust-adsorbed group were greater. At 3 days and 3 weeks, no significant differences between exposure groups were seen in any tissue except fat, where the amount of aflatoxins was greater for the dust-adsorbed group. AFB1 binding to DNA was significantly greater in the trachea and lung of the dust-adsorbed group compared to that in the microcrystalline group at 3 hr, whereas in the liver the AFB1-DNA binding in the microcrystalline group was significantly greater during this time. Thus, particle association of AFB1 increased the respiratory tract retention of this compound at early time intervals, which might be a factor in the reputed carcinogenic action of this compound in the respiratory tract. These findings may be useful as part of a comprehensive study to evaluate the disposition of AFB1 in individuals exposed to grain dusts laden with this carcinogen.

Absorption↗
PubMed1991

Isocratic high-performance liquid chromatography-photodiode-array detection method for determination of lysine- and arginine-vasopressins and oxytocin in biological samples.

A simple, isocratic, sensitive (1 ng), and specific high-performance liquid chromatographic (HPLC) method based on photodiode-array detection (PAD) is described for simultaneous quantitation of the bioactive peptides, lysine vasopressin (LVP), arginine vasopressin (AVP) and oxytocin (OXY). Acidified pig plasma and left ventricular (LV) tissue samples were first extracted with Sep-Pak C18 columns, and the bioactive peptides were eluted with methanol, then dried at 37 degrees C and reconstituted with HPLC mobile phase. The bioactive peptides were separated by HPLC on a Dynamax 3009-A C8 column with a mobile phase of 0.1% trichloroacetic acid-50 mM heptanesulfonic acid-30mM triethylamine-20% acetonitrile in water, pH 2.5 and identified with a Waters 990-PAD system (spectrum index plots in the range 200-400 nm). Standards of LVP, AVP and OXY and their mixtures showed a linear increase in the range 5 to 100 ng and were eluted at 6.1, 6.9 and 4.6 min, respectively. Spectrum analysis showed a distinct absorption peak at 280 nm, corresponding to peptide bonds. The reproducibility of the method coefficient of variation for standards is 6.9, 5.8 and 4.7% for LVP, AVP and OXY, respectively. In plasma and tissue it is much higher: 12.9% (LV tissue) and 18.6% (plasma) for LVP. Pig plasma contains negligible amounts of AVP and OXY; LVP is much higher (0.28 +/- 0.19 ng/ml). In pig tissue, LVP predominates (6.95 ng/g wet weight) compared to AVP (1.45) and OXY (1.50). Spectral analysis is necessary to identify the bioactive peptide peaks among interfering substances and to increase the sensitivity four-fold. The method described here is useful for the simultaneous determination of LVP, AVP and OXY in the nanogram range and can be extended to picogram levels by employing PAD spectral analysis techniques.

Animals↗
PubMed1991

Intracellular membrane fusion.

Protein trafficking and membrane assembly are accomplished in eukaryotes by the specific targeting and fusion of vesicles. In this review we describe some of the molecules implicated as components of the fusion apparatus, and evidence that suggests the same factors are recruited for a variety of intracellular fusion events.

Carrier Proteins↗
PubMed1991

Magnetic resonance imaging in the preoperative evaluation of cervical radiculopathy.

Forty patients with cervical radiculopathy were examined preoperatively with magnetic resonance imaging (MRI). MRI was used alone in 27 (68%) of the 40 patients; the remainder also had computed tomography in conjunction with myelography. The primary criterion on MRI for a clinically significant lesion was asymmetrical narrowing of the subarachnoid space in the region of the nerve root. Surgical confirmation of the abnormality was obtained in all 40 cases. The operative findings were a herniated nucleus pulposus (32 of 40 patients), spondylosis (2 of 40 patients), or a combination of the two (6 of 40 patients). MRI identified a surgical lesion (herniated nucleus pulposus, spondylosis, or both) in 37 of the 40 (92%) patients. We think MRI is the only preoperative imaging examination necessary in most cases of cervical radiculopathy.

Adult↗
PubMed1991

Roentgenographic assessment in hallux valgus.

Which simple roentgenographic angle should be used to assess medial (varus) deviation of the first metatarsal in cases of hallux valgus has been a topic of debate. Measurements were made from roentgenograms of 100 symptomatic feet in women with hallux valgus. These were compared with similar measurements obtained from symptomatic normal feet of women of a similar age distribution. The hallux valgus angle was associated with medial deviation of the first metatarsal measured by all three of the parameters defined and tested, i.e., the intermetatarsal, metatarsus primus varus, and metatarsus omnis varus angles. Of these, the best measure was the intermetatarsal angle, which in the hallux valgus feet differed significantly from controls more than the other measurements. No evidence was found to support any concept of second metatarsal deviation from normal.

Adolescent↗
PubMed1990

Comparative formation and removal of aflatoxin B1-DNA adducts in cultured mammalian tracheal epithelium.

Aflatoxin B1 (AFB1) DNA binding, adduct formation, and AFB1-DNA adduct repair were studied in tracheal explants from rabbit, hamster, and rat. These species vary in populations of cytochrome P-450-containing nonciliated tracheal epithelial cells. Explants were cultured in media containing 0.5 microM AFB1 for 12 h. After the 12-h treatment, the explants were cultured for time intervals up to 84 h and then analyzed for AFB1-DNA adducts. Binding of AFB1 to DNA was highest in rabbit tracheal explants (78 pmol/mg DNA), followed by the hamster (28 pmol/mg DNA), with the rat (3 pmol/mg DNA) showing minimal AFB1-DNA binding. Repair rates in the hamster and rat were constant over time with removal of the 8,9-dihydro-8-(N7-guanyl)-9-hydroxyaflatoxin B1 accounting for the majority of adduct disappearance. The rabbit demonstrated biphasic repair of adducts; all adduct types [8,9-dihydro-8-(2-amino-6-formamido-4-oxo-3,4-dihydropyrimid-5- ylamino)-9- hydroxyaflatoxin B1] were rapidly removed during the first 12 h posttreatment with AFB1, followed by a slower removal phase of primarily 8,9-dihydro-8-N7-guanyl)-9-hydroxyaflatoxin B1. After 84 h, 90, 72, and 55% of the initial adducts were removed in the rabbit, hamster, and rat, respectively. Labeled thymidine studies showed that cells of the tracheal epithelium did not turn over sufficiently to bias the apparent repair rates. These results demonstrated that carcinogen activation and repair capabilities of tracheal epithelium vary among species and that these processes likely relate to the presence of smooth endoplasmic reticulum containing nonciliated tracheal epithelial cells in those species.

Aflatoxin B1↗
PubMed1990

Comparative action of aflatoxin B1 in mammalian airway epithelium.

Aflatoxin B1 (AFB1) is thought to be an occupational risk factor for airway carcinogenesis where exposure to AFB1-laden grain dusts is common. Since activation of AFB1 is catalyzed by cytochromes P-450 associated with the smooth endoplasmic reticulum, we compared the response to AFB1 in cultured tracheal epithelium from species with abundant (rabbit and hamster) and scarce (rat and monkey) distributions of smooth endoplasmic reticulum in nonciliated tracheal epithelial cells. Explants from each species, incubated in medium containing 0.5 microM [14C]-AFB1 for selected intervals up to 24 h, were compared on the basis of binding of [14C]-AFB1 to tracheal DNA, amount and type of AFB1 metabolites in the medium, ultrastructurally determined population densities of epithelial cells, and distribution of bound material in epithelium as determined by autoradiographic grain densities. Cultures derived from rabbits were most active in metabolic conversion and formation of AFB1-DNA adducts, followed by those from hamsters, rats, and monkeys. Rabbit tracheal epithelium formed a significantly greater proportion of glutathione conjugates, while that from hamster formed a greater amount of AFB1-dihydrodiol, compared to rats and monkeys. The monkey formed significantly greater proportions of aflatoxin Q1 and the rabbit more aflatoxicol, compared to other species. There was selective degeneration and accumulation of labeled material in nonciliated cells in both rabbits and hamsters but not in rats or monkeys. Explants from rabbit tracheas were much more susceptible to cytotoxic injury and had higher autoradiographic grain densities than explants from hamsters. We conclude that the presence of smooth endoplasmic reticulum-containing nonciliated epithelial cells is qualitatively associated with the activation and toxicity of AFB1.

Aflatoxin B1↗