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Biomedical subjects

D Harding

Publications and source records attributed to D Harding.

At least 37 records · Page 2Linked to original sources
PubMed1989

Development of human liver UDP-glucuronosyltransferases.

The development of multiple UDPGT activities towards eight substrates has been studied in fetal term and adult post-mortem (less than 5 h after death) liver samples. Most fetal and term liver activities were less than 14% of adult values, except that towards 5-hydroxytryptamine which was present in fetal and term liver at adult levels. The majority of UDPGT activities develop to adult levels within 10-20 weeks postnatally, and even premature (30 weeks) which survive for up to 10 weeks will develop these enzyme activities. Immunoblot analysis of human liver microsomes and cDNA cloning of human UDPGT shows the existence of the family of isoenzymes in man, and it is important to determine the developmental pattern of individual drug glucuronidating enzymes in liver. Immunoblot analysis of developing liver shows the presence of two major UDPGT polypeptides in fetal liver, whereas more than five are observed in adult liver. The investigation of substrate specificity of individual UDPGTs by expression of cloned genes in COS-7 cells and the use of antibodies will facilitate the identification of enzymes present in perinatal liver.

Cloning, Molecular↗
PubMed1989

Elemental and structural studies of the rat galactose cataract.

A series of rat galactose lenses, from 1 to 20 days on the 50% galactose diet, were frozen in the whole eye, and fractured from pole to pole in the frozen state. Lyophilized half-lenses were prepared for analysis by energy dispersive spectrometry (EDS). Following elemental analysis, some specimens were embedded and sectioned for histological studies. Elemental X-ray maps, and/or profiles, were made for K, Na, Cl, Ca, P, and S. As early as two days on the galactose diet, a crescent-shaped region ("streak") of Cl, Na, and Ca gain, and K loss develops near the equatorial surface. Between this region and the equatorial surface are the nucleated differentiating fiber cells which maintain low Cl, Na, and Ca, and high K (viable equatorial zone, VEZ). With time the "streak" expands anteriorly, centrally and posteriorly, eventually (by 20 days) including most of the lens. The VEZ, including the epithelium, however, is non-reactive to the galactose diet, which is deleterious to the fully differentiated fiber cells. Eventually, the VEZ undergoes a characteristic morphological change, apparently due in part to changes in its physical environment.

Animals↗
PubMed1988

Cloning and substrate specificity of a human phenol UDP-glucuronosyltransferase expressed in COS-7 cells.

A rat kidney phenol UDP-glucuronosyltransferase cDNA was used to isolate a human liver phenol UDP-glucuronosyltransferase cDNA by screening of a human liver cDNA library in the expression vector lambda gt11. The 2.4-kilobase cDNA contained an open reading frame of 1593 base pairs coding for a protein of 531 residues. The human liver cDNA was subcloned into the vector pKCRH2. Transfection of this recombinant plasmid into COS-7 cells allowed the expression of a protein of approximately 55 kDa. The enzyme synthesized was a glycoprotein, as indicated by a reduction in molecular mass of approximately 3 kDa after biosynthesis in the presence of tunicamycin. The expressed enzyme rapidly catalyzed the glucuronidation of 1-naphthol, 4-methylumbelliferone, and 4-nitrophenol. The use of a related series of simple phenols provided an outline description of the substituent restrictions imposed upon the phenolic structures accepted as substrates. The glucuronidation of testosterone, androsterone, and estrone was not catalyzed by this cloned UDP-glucuronosyltransferase.

Amino Acid Sequence↗
PubMed1988

Examination of the substrate specificity of cloned rat kidney phenol UDP-glucuronyltransferase expressed in COS-7 cells.

A cDNA encoding a rat kidney UDP-glucuronyltransferase (UDPGT) was subcloned into the vector pKCRH2. Expression driven by the SV40 promoter produced enzymatically active UDPGT in COS-7 cells cultured in vitro. The appearance of enzyme activity was associated with an immunodetectable glycosylated UDPGT protein (Mr 53 kDa) in the cells. The expressed enzyme rapidly catalyzed the glucuronidation of 1-naphthol, 4-methylumbelliferone, and 4-nitrophenol. Studies using more than 20 compounds showed that the cloned UDPGT exhibited a restricted specificity towards planar phenols. A crude description of the molecular conformation of 4-alkylphenols accepted within the active site of the protein was obtained. The glucuronidation of morphine, thymol, menthol, testosterone, androsterone, or estrone was not catalyzed by this enzyme.

Animals↗
PubMed1987

Cloning of a human liver microsomal UDP-glucuronosyltransferase cDNA.

A cDNA clone (HLUG 25) encoding the complete sequence of a human liver UDP-glucuronosyltransferase was isolated from a lambda gt11 human liver cDNA library. The library was screened by hybridization to a partial-length human UDP-glucuronosyltransferase cDNA (pHUDPGT1) identified from a human liver pEX cDNA expression library by using anti-UDP-glucuronosyltransferase antibodies. The authenticity of the cDNA clone was confirmed by hybrid-select translation and extensive sequence homology to rat liver UDP-glucuronosyltransferase cDNAs. The sequence of HLUG 25 cDNA was determined to be 2104 base-pairs long, including a poly(A) tail, and contains a long open reading frame. The possible site of translation initiation of this sequence is discussed with reference to a rat UDP-glucuronosyltransferase cDNA clone (RLUG 38).

Animals↗
PubMed1987

Crohn's disease with pelvic abscess appearing as lumbar disc herniation.

Crohn's disease (regional enteritis) is a chronic inflammatory disease of the bowel with well-documented clinical manifestations and complications. This report of a 35-year-old woman with Crohn's disease outlines the clinical presentation and studies illustrating "quiescent" regional enteritis. The patient was treated for one of the complications of this disease entity. She was referred to the orthopedic clinic with symptoms of lumbar disc syndrome, as well as a painful hip. Crohn's disease was diagnosed and assumed to be well controlled. Physical examination revealed a subgluteal abscess, ostensibly caused by Crohn's disease. The abscess fistulized through the greater sciatic notch. The capricious nature of this disease entity is self-evident.

Abscess↗
PubMed1986

The isolation of genomic recombinants for the human apolipoprotein B gene and the mapping of three common DNA polymorphisms of the gene--a useful marker for human chromosome 2.

We have used four independently isolated cDNA probes for human apolipoprotein B (apo B), to isolate overlapping genomic recombinants for the 3' portion of the apo B gene. The cDNA clones and a unique fragment from the genomic recombinant have been used to identify the human apo B gene in DNA from a series of rodent X human somatic cell hybrids. Our results provide evidence for the assignment of this gene to the short arm of human chromosome 2 (p23-pter). We have used the cDNA probes to identify three common DNA polymorphisms. The first, detected with the restriction enzyme XbaI and our probe pAB4, has a rare allele frequency of 0.48. The other two polymorphisms are detected with the probe pAB3. The enzyme MspI detects at least three alleles, with frequencies of 0.67, 0.16 and 0.15, while that detected with the enzyme EcoRI has a rare allele frequency of 0.12. The relative position of these polymorphisms has been mapped using the genomic recombinants. Investigation of a small number of haplotypes indicates that there is linkage equilibrium between the polymorphisms, which have a total polymorphism information content (PIC) value of more than 0.8. These polymorphisms will provide useful markers for genetic studies on chromosome 2 and for the analysis of the involvement of variants of the apo B gene in the development of hyperlipidaemia.

Animals↗
PubMed1985

Effect of temperature on calcium exchange in digitonin-treated rat ventricular myocytes.

The effect of a change in temperature on net mitochondrial Ca2+ exchange has been investigated in a suspension of adult rat ventricular myocytes. Temperature was varied between 42 degrees C and 15 degrees C. Hypothermia reduced the initial rate of respiration-dependent Ca2+ uptake and reduced the Na+-sensitivity of Ca2+ efflux. The net result of these alterations is that at low temperatures, the Ca2+ level at which a steady-state between mitochondria and sarcoplasm is maintained, will be raised.

Animals↗
PubMed1985

Open reduction in depressed fractures of the os calcis.

Fifty-two patients with subtalar joint involvement secondary to os calcis fractures have been treated with a surgical technique designed by George F. Pennal. There were 23 tongue-type fractures and 33 joint depression fractures in this series. All were treated by open reduction and internal fixation, and occasionally also by bone grafting. Patients have been followed from two to seven years from the time of their injury, and the results indicate that 39 of the patients are relatively symptom-free and doing the same work as they had done prior to their injury. Nine patients have required some modification of their work, and four patients were classified as failures. Treatment of depressed fractures of the subtalar joint by this method produces relatively predictable results.

Adolescent↗
PubMed1981

Effects of captopril (SQ 14,225) in a patient with primary pulmonary hypertension.

In a 33-year-old patient with severe primary pulmonary hypertension, the acute administration of the angiotensin-converting-enzyme inhibitor captopril (SQ 14,225) induced a rise in cardiac output, and a fall in both pulmonary and systemic vascular resistance. Subsequent chronic oral administration of captopril induced only transient clinical improvement, and the patient died. Captopril may nevertheless be useful in the treatment of less advanced cases of this disease.

Adult↗