Search PubMed⌕ Search

Biomedical subjects

J H Wilson

Publications and source records attributed to J H Wilson.

At least 235 records · Page 13Linked to original sources
PubMed1986

Nonhomologous recombination in mammalian cells: role for short sequence homologies in the joining reaction.

Although DNA breakage and reunion in nonhomologous recombination are poorly understood, previous work suggests that short sequence homologies may play a role in the end-joining step in mammalian cells. To study the mechanism of end joining in more detail, we inserted a polylinker into the simian virus 40 T-antigen intron, cleaved the polylinker with different pairs of restriction enzymes, and transfected the resulting linear molecules into monkey cells. Analysis of 199 independent junctional sequences from seven constructs with different mismatched ends indicates that single-stranded extensions are relatively stable in monkey cells and that the terminal few nucleotides are critical for cell-mediated end joining. Furthermore, these studies define three mechanisms for end joining: single-strand, template-directed, and postrepair ligations. The latter two mechanisms depend on homologous pairing of one to six complementary bases to position the junction. All three mechanisms operate with similar overall efficiencies. The relevance of this work to targeted integration in mammalian cells is discussed.

Animals↗
PubMed1986

Effects of caloric deprivation on thyroid hormone tissue uptake and generation of low-T3 syndrome.

Changes in thyroid hormone metabolism in the low-3,5,3'-triiodothyronine (T3) syndrome cannot be fully explained in all conditions by a decrease in 5'-deiodinase activity. Recent observations showed that in rat hepatocytes iodothyronines are taken up by an active transport mechanism. To investigate whether regulation, i.e., inhibition of active transmembraneous transport for iodothyronines in humans may contribute to the generation of the low-T3 syndrome, tracer thyroxine (T4) and T3 kinetic studies were performed in 10 obese subjects before and after 7 days on a 240 kcal diet. Kinetics analyses were performed according to a three-pool model of distribution and metabolism for both T4 and T3. For T4 kinetics, during caloric deprivation serum total T4 and plasma pool did not change and production rate and metabolic clearance rate (MCR) were significantly lower. Despite a significantly higher serum free T4, the mass transfer rate to the rapidly equilibrating pool (REP) and the slowly equilibrating pool (SEP) diminished significantly, leading to smaller tissue pools. For T3 kinetics, both serum total T3, free T3, plasma pool, and production rate diminished significantly, while MCR remained unchanged. Mass transfer rates to the REP and the SEP were lowered by approximately 50%, leading to smaller tissue pools. These changes cannot be fully explained by a similar decrease of serum free T3 (only 25%), indicating a diminished transport efficiency for T3. In conclusion, during caloric restriction, transport of T4 and T3 into tissues is diminished, and this phenomenon is much more pronounced for T4 than for T3.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

A retrospective study of proliferative interstitial lung disease of horses in Florida.

Proliferative and fibrosing interstitial lung disease was diagnosed in 20 horses submitted for necropsy between 1982 and 1985. Most of the horses were foals ranging from 3 days to 6 months in age. Six adult horses were affected. The macroscopic and microscopic characteristics of the lesions consisted of proliferative interstitial pneumonia and were similar to those of atypical interstitial pneumonia of ruminants. Based on morphologic features of the lesions, a toxic etiology is suspected for the induction of this naturally acquired primary equine lung disorder, but could not be specifically discovered by historical information.

Animals↗
PubMed1985

Occipito-atlanto-axial malformation with atlanto-axial subluxation in an ataxic calf.

Occipito-atlanto-axial malformation with atlanto-axial subluxation was diagnosed radiographically in a 4-day-old Holstein calf with a short neck, symmetric ataxia, and tetraparesis, indicative of a cervical spinal cord lesion. Necropsy confirmed the clinical diagnosis and revealed ribs on C-7, with partial fusion of C-7 and T-1. Histologic examination revealed focal degeneration of the spinal cord in the second cervical segment at the level of the atlanto-axial joint and extensive secondary neuronal fiber degeneration possibly caused by spinal cord trauma that occurred in utero.

Animals↗
PubMed1985

The involvement of iron and lipid peroxidation in the pathogenesis of HCB induced porphyria.

Hexachlorobenzene (HCB) induces a porphyria characterized by a diminished activity of the enzyme uroporphyrinogen decarboxylase (URO-D), presumably due to inactivation by reactive metabolites of HCB. We studied the effect of iron on HCB porphyria in female rats, to determine whether the iron dependent process of lipid peroxidation was involved in the pathogenesis of porphyria. We showed that malondialdehyde formation is increased in rat liver tissue of porphyric rats and that high molecular weight proteins due to cross-linking are formed. We also showed that the induction of porphyria by HCB is dependent on the presence of iron. Our findings suggest that lipid peroxidation is involved in the toxicity of HCB and that the aggravating effects of iron on HCB are mediated by lipid peroxidation.

Animals↗
PubMed1985

Collaboration between psychiatrists and other professionals in a remand and assessment centre.

A referral system used in a remand and assessment centre for behaviourally disturbed boys is described. The psychiatric input to the centre is undertaken in the context of a multidisciplinary approach. The aim of the present study was to assist non-psychiatrically trained staff to make suitable referrals to psychiatrists. This enables the psychiatrist to work with the institution as a whole, without neglecting the needs of individual boys.

Adolescent↗
PubMed1985

Primary malignant tumours of the duodenum.

The clinical and radiological findings in 19 patients with primary duodenal malignancy are described. Weight loss, abdominal pain, nausea and vomiting were the main symptoms. Diagnosis was made by endoscopy or ERCP (71%) or by barium studies (68%). In retrospect the tumour was visible in 97% of the studies. Tumour growth was longitudinal, circular or spiral, the inner curvature being involved over a greater length than the outer curvature. Exophytic tumour growth, involvement of the papilla of Vater, malignant spikes, transient, non-constant tumour image, skip lesions and ulceration were often seen. Mean survival time was 18 months from start of symptoms in 10 inoperable patients, and 24 months in 9 patients undergoing resection.

Adenocarcinoma↗
PubMed1985

Relative rates of homologous and nonhomologous recombination in transfected DNA.

Both homologous and nonhomologous recombination events occur at high efficiency in DNA molecules transfected into mammalian cells. Both types of recombination occur with similar overall efficiencies, as measured by an endpoint assay, but their relative rates are unknown. In this communication, we measure the relative rates of homologous and nonhomologous recombination in DNA transfected into monkey cells. This measurement is made by using a linear simian virus 40 genome that contains a 131-base-pair duplication at its termini. Once inside the cell, this molecule must circularize to initiate lytic infection. Circularization can occur either by direct, nonhomologous end-joining or by homologous recombination within the duplicated region. Although the products of the two recombination pathways are different, they are equally infectious. Since homologous and nonhomologous recombination processes are competing for the same substrate, the relative amounts of the products of each pathway should reflect the relative rates of homologous and nonhomologous recombination. Analysis of individual recombinant genomes from 164 plaques indicates that the rate of circularization by nonhomologous recombination is 2- to 3-fold higher than the rate of homologous recombination. The assay system described here may prove to be useful for testing procedures designed to influence the relative rates of homologous and nonhomologous recombination.

Animals↗
PubMed1985

Effect of body size and cage profile on the shear strength of bones of caged layers.

The effects of body size and cage profile on the shear strength of bones from caged layers aged 72 weeks were studied. Bones tested included the radius, ulna, humerus, femur, and tibiotarsus. The ultimate shear force of the femur, tibia, and humerus all increased as body size increased (P less than 0.01). The wing bones of birds housed in high profile cages had higher shear breaking loads than birds housed in low profile cages. The ultimate shear stresses of the bones were not affected by body size or cage profile. The radius had the highest shear stress (29.2 MPa), followed in descending order by the ulna (19.1 MPa), tibiotarsus, humerus (11.4 MPa) and femur (11.3 MPa).

Animals↗
PubMed1985

Intragastric prostaglandin E2 and the prevention of gastrointestinal hemorrhage in ICU patients.

The effects of intragastric prostaglandin E2 (PGE2) on the occurrence of acute GI hemorrhage in intensive care patients were investigated in a prospective, double-blind, placebo-controlled study. Ninety patients with two or more risk factors (major surgery, multiple trauma, respiratory insufficiency, renal insufficiency, jaundice, hypotension, peritonitis, sepsis) were randomized for treatment with either PGE2 (0.5 mg) or placebo, administered every 4 h via a nasogastric tube. Blood loss in gastric aspirates was measured by 51Cr-erythrocyte labeling and a peroxidase test (orthotolidine). Of 57 patients who could be evaluated, 29 received PGE2 and 28 received placebo. Hemorrhage occurred in nine PGE2 patients and 13 placebo-treated patients, not a significant difference. The occurrence of hemorrhage was related to the number of risk factors, and GI hemorrhage was rarely the major factor determining mortality. Results of the orthotolidine test were not positively correlated with those of erythrocyte labeling, indicating that peroxidase tests should not be relied upon to detect blood in gastric aspirates.

Adolescent↗
PubMed1985

Production of leukotrienes and prostaglandins by human ascites cells.

Ascites was collected from six patients with liver cirrhosis and the cells isolated. These cells, mainly macrophages, were labelled with 14C-arachidonic acid and stimulated with the calcium ionophore A23187. The metabolites formed were separated by HPLC. The main substances formed by the ascites cells were leukotriene B4, 5-hydroxy-6,8,11,14 eicosatetraenoic acid and leukotriene C4. Smaller amounts of thromboxane B2, 12-hydroxy-5,8,10 heptodecatrienoic acid and 6-keto-prostaglandin F1 alpha were isolated. Human peritoneal macrophages are therefore capable of producing leukotrienes and prostaglandins. Production of these substances might play a role in some of the complications of patients with liver cirrhosis and ascites.

Arachidonic Acid↗