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Biomedical subjects

A Gardner

Publications and source records attributed to A Gardner.

At least 73 records · Page 4Linked to original sources
PubMed1992

Paternal origin of 11p15 duplications in the Beckwith-Wiedemann syndrome. A new case and review of the literature.

A boy suffering from the Beckwith-Wiedemann syndrome (BWS) was found to have partial trisomy of the short arm of chromosome 11 [46,XY,der(5)t(5;11)(p15.2;p14)]. Both his parents were phenotypically normal, but his father carried a balanced translocation between chromosomes 5 and 11 [46,XY,t(5;11)(p15.2;p14)]. DNA analysis of polymorphic markers on 11p15 confirmed the paternal origin of the duplicated material in the child. This case is the sixth report of paternal duplication of 11p15 in BWS. These results are discussed in relation to the possible role of genomic imprinting in BWS and in Wilms' tumor.

Beckwith-Wiedemann Syndrome↗
PubMed1992

Purification and Properties of Fructokinase from Developing Tubers of Potato (Solanum tuberosum L.).

Fructokinase has been purified from developing potato (Solanum tuberosum L.) tubers by a combination of hydrophobic interaction, affinity chromatography, and gel filtration. The protein has a native molecular mass of approximately 70 kD but is apparently a dimer. Ion-exchange chromatography and two-dimensional western blots resolved three major fructokinases, designated FK-I, FK-II, and FK-III in order of their elution from a Mono-Q column. Fructokinase activity proved labile when proteins were purified in the absence of fructose. Kinetically, FKs I, II, and III all have broad pH optima with peaks at about pH 8.5. The enzymes have a high specificity for fructose (K(m) values ranging from 0.041 to 0.128 mm), and can utilize a range of nucleoside triphosphates. Unlike FKs I and II, FK-III is not inhibited by fructose concentrations in excess of 1 mm. MgADP inhibited activity of the three FKs (between 68 and 75% inhibition at 1.0 mm), whereas fructose 6-P caused inhibition at concentrations of 10 mm. There were no regulatory effects observed with a range of other metabolites. K(+) (10 mm) activated FK-I by 4-fold and FKs II and III by only about 50%.

Journal Article↗
PubMed1991

Effect of temperature reduction on responsiveness to cholinomimetics in the taenia caeci of the guinea-pig.

1. The effect of temperature reduction on the interaction of carbachol (CCh) and McN-A-343 (McN) with muscarinic receptors in the guinea-pig taenia caeci was investigated. 2. McN, a partial agonist, acted on the smooth muscle to produce contraction. The response was unaffected by tetrodotoxin and the pKB for inhibition by pirenzepine was 6.8, indicating that ganglionic M1 receptors were not involved in the response. 3. Reduction in temperature from 37 degrees C to 18 degrees C for 3 h led to a marked reduction in the contractile response to McN (2-200 microM) but no reduction in the response to CCh (0.1-3 microM). 4. The reduction in temperature was not accompanied by any change in the affinity of McN or CCh for muscarine receptors in binding experiments with [3H]-QNB. 5. The KA value for CCh determined after irreversible receptor inactivation with propylbenzilylcholine mustard followed by ca 60-min wash-out was 7.6 microM, a value similar to that obtained in binding experiments. 6. The EC50 for McN in producing contraction at 37 degrees C (2.1 microM) was similar to the KA value for the partial agonist obtained in experiments with the irreversible antagonist phenoxybenzamine (2.5 microM). It was also similar to the KB value determined at 18 degrees C (3.4 microM) when McN could be used as an antagonist of contractions to CCh. 7. At 18 degrees C, phosphatidylinositol (PI) hydrolysis by CCh was reduced to 23% of that at 37 degrees C. 8. It is concluded that reduction of muscarinic receptor activation of the PI pathway by cholinomimetics with lowering of the temperature could account for the findings with McN on contractility.

(4-(m-Chlorophenylcarbamoyloxy)-2-butynyl)trimethy↗
PubMed1991

Pyrimethamine-sulfadoxine (Fansidar) resistance in a non-immune Kenyan--a case report.

Drug resistance in an endemic zone is often difficult to prove. This case illustrating both chloroquine and pyrimethamine sulfadoxine resistance unfolded in an area without risk of reinfection. The long time lapse and hence danger, between exposure and clinical symptoms in those on chemoprophylaxis highlighted and emphasis is placed on adequate follow up to pick up resistance in long acting preparations.

Animals↗
PubMed1990

Environmental findings and sudden infant death syndrome.

Sudden infant death syndrome (SIDS) death rates show substantial seasonal variation. Analysis of this variation shows that it is due to postnatal factors. Possible variables are temperature, infection, pollution, and the infants' interaction with the social environment. In England and Wales the temporal pattern of pollution levels and the geographical variation of death rates do not suggest pollution is generally an important factor. Social environment appears the most important. One in three high risk infants are in families with multiple social problems compared with 9% of controls. Further studies of why some infants are at greatly increased risk might identify crucial adverse environmental factors and indicate how some deaths could be prevented.

Air Pollution↗
PubMed1988

Prevention of unexpected infant death. A review of risk-related intervention in six centers.

Over seventy percent of unexpected infant deaths are registered as SIDS. Over 85,000 infants have been screened at birth and one month of age for risk of unexpected death using the Sheffield Score system. Scores range from below 400 to over 800 points. Infants with scores over 800 are at more than 16 times greater risk than infants with scores below 400. Family doctors and health visitors were alerted to high-risk infants, who were examined at home and weighed naked at home five times in the first six months. Mortality in the high-risk group was reduced by more than 50% (p less than 0.02 in one area and p less than 0.05 in another). It is concluded that with few extra resources unexpected infant mortality can be reduced by 25% by this approach.

Child Health Services↗
PubMed1988

Whooping cough and unrecognised postperinatal mortality.

Trends in postperinatal infant mortality from respiratory causes and the sudden infant death syndrome in England and Wales for 1968 to 1984 were examined. These were compared by time series analysis with changes in the incidence of specific infective diseases and organisms for the same period. Discontinuity was found in association with the occurrence of whooping cough between 1977 and 1982. Associations with the general incidence of respiratory infections and other specific organisms were less evident. An estimate of excess mortality is 460 to 700 deaths, a substantial increase over the certified mortality from whooping cough.

Disease Outbreaks↗
PubMed1986

Monoclonal antibodies raised against a subsequence of senile plaque core protein react with plaque cores, plaque periphery and cerebrovascular amyloid in Alzheimer's disease.

Four monoclonal antibodies (1D2/1/2, 1G10/2/3, 3B6/1/1, 4D12/2/6) were raised against a synthetic peptide consisting of residues 8-17 of a protein reported to be common to senile plaque cores, cerebrovascular amyloid and neurofibrillary tangles in Alzheimer's disease. In an immunoperoxidase study of Alzheimer brain tissue, these antibodies stained plaque and vascular amyloid but not tangles, suggesting that the polypeptide chain in the region of residues 8-17 is exposed in the former two but, if present, inaccessible in the latter. In addition, staining of granular material in the plaque periphery was observed. These antibodies will be useful tools for future work on the origin of this protein.

Alzheimer Disease↗
PubMed1986

Increased glutathione peroxidase activity in erythrocytes in patients with Alzheimer's disease/senile dementia of Alzheimer's type.

Glutathione peroxidase (GSH-Px) activity in erythrocytes was studied in 9 patients with Alzheimer's disease/senile dementia of Alzheimer's type (AD/SDAT) of ages 34-64 years and compared with that in 16 healthy controls of ages 21-66 years. The median GSH-Px activity in erythrocytes from AD/SDAT patients was 408, mu kat/1 (range 338-500 mu kat/1) and that from healthy controls 348, mu kat/1 (range 258-439 mu kat). This difference was significant (p less than 0.005) Wilcoxon rank test. Since there are great clinical and pathological similarities between AD/SDAT and the dementia of Down's syndrome (DS) patients and since both these groups of patients have increased activity of the selenium-dependent enzyme GSH-Px, it is suggested that there could be a similar metabolic background of the dementia. Many findings in the oxidative metabolism of DS suggest increased oxidative damage with an elevation of the turnover of superoxides to peroxides within cells and with a secondary biochemical modification such as increase in tissual GSH-Px activity. A similar mechanism with elevated peroxidation within cells might be responsible for the present finding of increased GSH-Px activity in erythrocytes and for the development of dementia in AD/SDAT.

Adult↗
PubMed1986

Why did postperinatal mortality rates fall in the 1970s?

Postperinatal mortality rates have shown two phases of decline since 1947 which are traditionally ascribed to social and medical improvements. These factors cannot, however, explain the arrest of decline during the 1960s. There appears to be a biological effect on child mortality rates, manifesting as a generation effect. This is due partly to continuing changes in the structure of the child population, itself a consequence of social and biological changes among the parent generation when they were children. In this study national and selected urban postperinatal deaths have been divided into two categories: "probably inevitable" and "possibly preventable". The continuing prevalence of "possibly preventable" deaths gives cause for concern. If the number of these deaths is to be further reduced, reconsideration and redeployment of community child health staff may be necessary.

Communicable Diseases↗
PubMed1984

Patency in canine inferior vena cava grafting: effects of graft material, size, and endothelial seeding.

We studied 117 inferior vena cava (IVC) replacements in dogs to determine the effects of graft material, graft size, endothelial seeding, and cultured endothelial linings on graft patency. As a control, the IVC was removed and reimplanted in 11 dogs. Dacron (n = 7) and expanded polytetrafluoroethylene (e-PTFE) grafts (n = 12) were seeded immediately with the use of enzymatically derived autogenous jugular vein endothelium. Cultured linings were prepared for e-PTFE grafts (n = 9) by inoculating the graft with jugular endothelium and nurturing the lining in tissue culture for 14 to 30 days before implantation. Unseeded grafts (n = 27) were prepared according to the manufacturer's recommendations. These six methods of preparation were tested in grafts measuring 6 mm I.D. and 60 mm in length. Other sizes were tested with a Latin square study design. After 30 to 60 days the grafts were perfusion fixed and studied with light and transmission electron microscopy. Patency was determined by contrast cavography after 7 and 30 days. Patency in the IVC reimplantation was 100% compared with 28.0% of the e-PTFE (p = 0.001) and none of the Dacron grafts that measured 6 mm I.D. and 60 mm long. e-PTFE and Dacron graft patency also differed significantly (p = 0.035). Seeded and culture-lined e-PTFE grafts in that same size were patent in 31.6% compared with 16.7% of unseeded e-PTFE. With grafts measuring 80 mm long, three of the five e-PTFE grafts were patent between 3 and 7 days. All progressed to occlusion by 30 days and compared poorly with all other graft sizes tested (2.6% progression to occlusion [p = 3 X 10(-8)]). Recanalization was not seen in 10 occluded grafts that were followed for 60 days. The histologic features of seeded grafts differed remarkably from grafts previously studied in the arterial circulation and from culture-lined and unseeded venous prostheses in that 60% had prominent large, random, endothelium-lined channels within the inner capsule. Larger graft diameters (p = 0.009) and the omission of an endothelial surface treatment (p = 0.004) were associated with anastomotic subendothelial fibrous hyperplasia. We conclude that graft material is the major determinant of patency in IVC replacements, that an extensive endothelial surface promotes patency, but that simply seeding e-PTFE or Dacron grafts with 10(5) endothelial cells does not provide sufficient endothelium to alter early patency.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1984

Behavior and bladder disturbance of enuretic children: a rational classification of a common disorder.

A group of 126 enuretic children were evaluated as to their psychiatric and neurological states, functional bladder volume and environmental circumstances. Few differences were found when the children were grouped according to presence or absence of social disadvantage, the presence of a family history of enuresis, or the nature of onset of enuresis. No classification differentially predicted response to treatment. However, children with an associated psychiatric disorder had significantly lower bladder volumes and had more developmental delays. It is concluded that the classifications of primary or secondary enuresis, or familial or non-familial, etc., are of little practical value. When psychiatric disorder is found, it is probably related to other constitutional abnormalities. Rather than there being two separate groups of enuretic children with behavior disorder and low functional bladder volume, these two abnormalities are found in conjunction.

Child↗
PubMed1984

Down's syndrome with a recombinant tandem duplication of chromosome 21 derived from a maternal ring.

An account is given of the cytogenetic investigations of a girl with Down's syndrome found to have a dicentric duplication of chromosome 21. This tandem type of rearrangement was interpreted as a recombinant derived from a single meiotic crossover between a maternal ring 21 and its normal homologue. A population of cells was also found in which breakage of the dicentric resulted in a chromosome 21 with a small terminal deletion. The mother and the proband's younger brother, who was also a ring 21 heterozygote, were both clinically normal.

Adult↗
PubMed1984

Seeding human arterial prostheses with mechanically derived endothelium. The detrimental effect of smoking.

Endothelial healing of Dacron arterial prostheses can be hastened in dogs by seeding autogenous venous endothelium onto the prostheses in a single-staged operation. To determine whether this technique enhances the patency of human grafts, we studied the results of 186 operations on 161 patients performed between February 23, 1978, and December 1, 1982. Alternately allocating patients to treatment with seeded and unseeded Dacron knitted prostheses, we performed axillary-femoral and axillary-femoral-femoral bypasses in 11 patients (six seeded and five unseeded) and femoral-femoral bypasses in 28 (13 seeded and 15 unseeded). By a randomized block method of treatment allocation, femoral-popliteal grafts were installed in 147 limbs (112 vein, 18 seeded, and 17 unseeded). Patency was analyzed by the life-table method. Overall, femoral-femoral and femoral-popliteal bypasses demonstrated no difference between the seeded and unseeded grafts. Patency was somewhat better in seeded than unseeded axillary-femoral bypasses. Nevertheless, nonsmokers with seeded femoral-popliteal Dacron grafts enjoyed a significantly better graft patency than those with unseeded grafts (p = 0.035), whereas a substantial deterioration of seeded Dacron grafts was observed in those patients who smoked (p = 0.008 at 6 months). Vein grafts performed better than either seeded or unseeded Dacron prostheses (p = 0.016). Serum beta-thromboglobulin (BTG) levels varied widely and did not differ among any of the treatment groups. We concluded that endothelial seeding improved the patency of human arterial prostheses but that results were worse if the patient was a smoker. BTG was not a useful measure of the platelet activation induced by an arterial prosthesis.

Blood Coagulation Disorders↗
PubMed1984

Endothelial seeding of Dacron and polytetrafluoroethylene grafts: the cellular events of healing.

To detect cellular differences in the healing of polytetrafluoroethylene (e-PTFE) and Dacron grafts up to 7 months after implantation, we studied 108 aortic graft interpositions in dogs. Each prosthesis was alternately prepared by endothelial seeding or by an unseeded control method. The grafts were perfusion fixed and studied with light, scanning, and transmission electron microscopy at intervals from before to 221 days after implantation. Seeding resulted in the development of an extensive endothelial flow surface in two out of three of the e-PTFE and none out of four of the Dacron grafts by 10 days after implantation (p = 0.053). After 30 days a microfibrillar subendothelial matrix ranging from 5 to 11 mu formed in all but three grafts with endothelial coverage. The inner capsule of mature Dacron grafts was significantly thicker (169 +/- 143 mu) than in e-PTFE grafts (22 +/- 32 mu; p = 0.002). Seeded and unseeded Dacron grafts had predominantly fibroblasts in the outer capsule of the graft by 10 days. Surface endothelium, vasa vasorum, fibroblasts, and myointimal cells appeared in the inner capsule between 10 and 30 days after implantation. In Dacron grafts, fibroblasts and myointimal cells predominated in the inner capsule at 30 days, with smooth muscle cells not being definitely identifiable until after 150 days. Neither fibroblasts nor myointimal cells were common (present but sparse in one of four e-PTFE grafts) at 30 days, and transmural vasa vasorum were never seen. The seeded endothelial cells migrated rapidly from the sites of initial adhesion near the e-PTFE onto the flow surface. Only one of four of the unseeded e-PTFE grafts had surface endothelium after 30 days, and only moderate coverage developed during 180 days. We conclude that endothelial healing is more rapid in seeded e-PTFE grafts than in seeded Dacron grafts and occurs by a different mechanism.

Animals↗