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Biomedical subjects

J A Webb

Publications and source records attributed to J A Webb.

At least 91 records · Page 5Linked to original sources
PubMed1984

Maldescended testes and fertility: a review of 68 cases.

We report an analysis of 68 of 1112 couples who attended an infertility clinic where the man had past or present evidence of testis maldescent. The age at orchiopexy for these 68 men was later than would be expected, taking into account surgical practice in Scotland for the relevant time period and this supports the view that late orchiopexy is a risk factor for subsequent infertility. There was no evidence that antisperm antibodies are responsible for the damage to spermatogenesis in unilateral cases; however, measurement of the serum hormones showed elevations of LH and FSH which cannot be entirely explained as secondary to the damaged spermatogenesis. There was weak but nevertheless significant evidence that testis maldescent may be a poor prognostic factor as far as subsequent fertility is concerned and that this is independent of the length of time the couple have been trying and the man's motile sperm density. In two men there was intra-abdominal undescent and both were found to have testis tumours; we would re-emphasise that abdominal exploration is mandatory in such cases.

Adult↗
PubMed1984

The role of the distal nephron mechanisms in the concentration of contrast medium in the urine.

The concentrating mechanisms affecting contrast medium in the distal nephron have been studied using three contrast media of differing osmolality (monomer, dimer and non-ionic compounds) in antidiuretic dogs with three different basal solute excretion rates. Evidence has been obtained that, under conditions of contrast medium osmotic diuresis, the loop of Henle generates more free water. If the free water generated in response to the contrast medium solute load is reabsorbed in the collecting ducts, this can in part mask the different proximal tubular effects of contrast media of different osmolality. However, as basal solute excretion increases, the compensatory mechanism is overwhelmed and urine osmolality falls exponentially. At the higher basal solute excretion rates, different osmolar loads of contrast medium no longer produce different urine osmolalities and different urine contrast medium concentrations. It is therefore considered unlikely that contrast media of reduced osmolality will produce significant increases in urine contrast medium concentration under the conditions of solute diuresis which occur in renal failure.

Animals↗
PubMed1984

The effect of intravenous contrast medium on glomerular filtration rate.

The changes in glomerular filtration rate (GFR) after intravenous contrast medium have been investigated with three contrast media of differing osmolality (monomer, dimer and non-ionic agent) in antidiuretic dogs with three different basal solute excretion rates. A transient increase in GFR after contrast medium was attributed to the wash-out of medullary creatinine at the onset of diuresis. The subsequent fall in GFR was greatest with the contrast media of higher osmolality and in those dogs without an underlying solute diuresis. With the monomer, the decrease in GFR produced a significant decrease in the amount of contrast medium excreted in the first few minutes after contrast injection. It is suggested that an important factor in the decrease in GFR is the rise in pressure in the renal tubules at the start of a diuresis, before they have had time to dilate. An underlying solute diuresis is considered to protect against the fall in GFR because tubular dilatation has already occurred in response to the basal solute load. The decrease in blood pressure during and after contrast medium injection did not correlate with the fall in GFR.

Animals↗
PubMed1984

Can ultrasound and computed tomography replace high-dose urography in patients with impaired renal function?

Ninety-one patients with unexplained impaired renal function were investigated by high-dose urography, ultrasound and computed tomography (CT) without contrast. The aim was to evaluate the role of ultrasound and CT in renal failure, in particular their ability to define renal length and to show collecting system dilatation. In the majority of patients, renal length could be measured accurately by ultrasound. Measurements were less that those at urography because of the absence of magnification. Renal measurement by CT was not a sufficiently accurate indicator of renal length to be of clinical use. Both ultrasound and CT were sensitive detectors of collecting system dilatation: neither technique missed any case diagnosed by urography. However, in the presence of staghorn calculi or multiple cysts, neither ultrasound nor CT could exclude collecting system dilatation. CT was the only technique which demonstrated retroperitoneal nodes or fibrosis causing obstruction. It is proposed that the first investigation when renal function is impaired should be ultrasound, with plain films and renal tomograms to show calculi. CT should be reserved for those patients in whom ultrasound is not diagnostic or in whom ultrasound shows collecting system dilatation but does not demonstrate the cause. Using this scheme, ultrasound, plain radiography and CT would have demonstrated collecting system dilatation and, where appropriate, shown the cause of obstruction in 84 per cent of patients in this series. Only 16 per cent of patients would have required either high-dose urography or retrograde ureterograms.

Adolescent↗
PubMed1983

Partial Purification and Properties of an Alkaline alpha-Galactosidase from Mature Leaves of Cucurbita pepo.

A fourth molecular from of alpha-galactosidase, designated L(IV), an alkaline alpha-galactosidase, was isolated from leaves of Cucurbita pepo and purified 165-fold. It was active over a narrow pH range with optimal hydrolysis of p-nitrophenyl-alpha-d-galactoside and stachyose at pH 7.5. The rate of stachyose hydrolysis was 10 times that of raffinose. K(m) determinations in McIlvaine buffer (200 millimolar Na(2)-phosphate, 100 millimolar citric acid, pH 7.5) for p-nitrophenyl-alpha-d-galactoside, stachyose, and raffinose were 1.40, 4.5, and 36.4 millimolar, respectively. L(IV) was partially inhibited by Ca(2+), Mg(2+), and Mn(2+), more so by Ni(2+), Zn(2+), and Co(2+), and highly so by Cu(2+), Ag(2+), Hg(2+) and by p-chloromercuribenzoate. It was not inhibited by high concentrations of the substrate p-nitrophenyl-alpha-d-galactoside or by myo-inositol, but alpha-d-galactose was a strong inhibitor. As observed for most other forms of alpha-galactosidase, L(IV) only catalyzed the hydrolysis of glycosides possessing the alpha-d-galactose configuration at C(1), C(2), and C(4), and did not hydrolyze p-nitrophenyl-alpha-d-fucoside (alpha-d-galactose substituted at C(6)). The enzyme was highly sensitive to buffers and chelating agents. Maximum hydrolytic activity for p-nitrophenyl-alpha-d-galactoside was obtained in McIlvaine buffer (pH 7.5). In 10 millimolar triethanolaminehydrochloride-NaOH (pH 7.5) or 10 millimolar Hepes-NaOH (pH 7.5), hydrolytic activity was virtually eliminated, but the addition of low concentrations of either ethylenediaminetetraacetate or citrate to these buffers restored activity almost completely. Partial restoration of activity was also observed, but at higher concentrations, with pyruvate and malate. Similar effects were found for stachyose hydrolysis, but in addition some inhibition of L(IV) in McIlvaine buffer, possibly due to the high phosphate concentration, was observed with this substrate. It is questionable whether the organic acid anions possess any regulatory control of L(IV)in vivo. It was possible that the results reflected the ability of these anions, and ethylene-diaminetetraacetate, to restore L(IV) activity through coordination with some toxic cation introduced as a buffer contaminant.

Journal Article↗
PubMed1982

A preliminary investigation of radiation dose reduction on an EMI CT5005 whole body scanner using a copper wedge.

The effects of the existing filtration system upon a narrow, parallel beam of X rays were considered. The profile of a Cu filter to be placed on the tube-side A1 wedge was calculated on the basis that the total energy incident on the detector box would remain unchanged when the other A1 wedge was removed. A Cu wedge was machined according to this profile. The effects of this modification on surface radiation dose delivered to a 25 cm EMI water phantom were both predicted and measured for horizontal traverses, and were in broad agreement. The reduction in integral radiation dose to the 25 cm water phantom was predicted as 39%. Dose reductions measured at several points on the surface and within an Alderson Rando anthropomorphic phantom head averaged 53% and 20% respectively. The modified system was evaluated in terms of imaging ability, and although some degradation was seen, images of the EMI composite phantom remained "diagnostic" in quality, despite non-ideal responses of some photomultiplier tubes at intermediate and extreme positions of the traverse periphery.

Copper↗
PubMed1981

Renal function after high dose urography in patients with renal failure.

A retrospective study of 40 patients with moderate to severe renal failure who had high dose urography showed that none developed oliguric acute renal failure after the urogram. In 37 patients there was no worsening in renal function attributable to the urogram. This group included five patients in whom renal function was already deteriorating at the time of the urogram. In three patients a transient rise in serum creatinine without oliguria occurred in the week following urography. Differences between the British and North American experience are discussed.

Acute Kidney Injury↗
PubMed1981

The effect of DDAVP on intravenous urography.

The possible role of an antidiuretic hormone analogue, DDAVP (1 deamino-8-D-arginine vasopressin), in intravenous urography has been studied. The minimum effective dose of intravenous DDAVP in normal hydrated subjects was shown to be 2 ng/kg. During intravenous urography in fluid restricted subjects, a dose of 1 microgram DDAVP was necessary to reduce significantly the urine flow rate after contrast medium injection. Although the mean pyelographic score after DDAVP was increased, the differences observed were not statistically significant. The possible reasons for this finding are discussed.

Arginine Vasopressin↗
PubMed1980

Actinomycins and intrauterine contraceptive devices: the clinicopathologic study.

Since their widespread introduction in the early 1960s, IUD have been considered effective and safe. Early studies revealed the ability of the cavum uteri to regain bacteriologic sterility within 4 weeks of insertion. However, experience with long-term use indicates an enhanced risk of pelvic inflammatory disease, often of proven bacterial origin. Of these pelvic infections the most pernicious are those caused by Actinomyces. We present nine cases of actinomycotic female genital tract infection encountered in the past 3 years. The features of a distinct clinicopathology entity of IUD-associated actinomycotic pelvic disease are described. This disease is one of subtle protean manifestations and is not often diagnosed preoperatively. The most significantly pathogenic factors appear to be the duration of IUD use and the demonstrated relationship between IUD usage and infestation of the vagina with Actinomyces organisms.

Actinomycosis↗
PubMed1978

Distribution of alpha-Galactosidase in Cucurbita pepo.

The distribution of alpha-galactosidase (alpha-d-galactoside galactohydrolase [EC 3.2.1.22]) in Cucurbita pepo has been determined in an attempt to assess its involvement in hydrolysis of transport sugars of the raffinose oligosaccharide series ([alpha-1-6-0-galactopyranosyl](n) sucrose). Extracts prepared from leaves and petioles at different stages of development, roots, flowers, dry and germinating seeds, all contained appreciable levels of alpha-galactosidase activity. Chromatography of these extracts on DEAE-Sephadex resolved the enzyme into three active isozymic forms. These isozymes were present in all regions of the plant analyzed but their relative proportions varied between tissues and changed within leaf and petiole tissues during development and in seeds during their germination. The level of total alpha-galactosidase activity in the leaf blade measured on a fresh weight or total protein basis remained constant at all developmental stages analyzed. The occurrence of these isozymes in mature exporting leaves indicates an effective intracellular compartmentation between their location and the sites of galactosyl oligosaccharide biosynthesis, accumulation and movement in the tissue. We have used these results to comment on the transport pathway of galactosyl oligosaccharides between the phloem and surrounding tissues in this plant.

Journal Article↗
PubMed1978

The effect of osmotic diuresis on urinary iodine concentration using contrast media of differing osmolality.

The urinary iodine concentrations of a monomer (sodium iothalamate), a dimer (sodium iocarmate) and a non-ionic compound (metrizamide) have been compared in dogs with varying levels of solute excretion. All the animals were undergoing maximal antidiuresis. In dogs with normal solute excretion, metrizamide and iocarmate produced higher urinary iodine concentrations than iothalamate. There was no significant difference between metrizamide and iocarmate. With increasing levels of solute excretion, the differences between the compounds were reduced. These findings suggest that contrast media of reduced osmolality are unlikely to have a special place in advanced renal failure.

Animals↗
PubMed1976

Intensive investigation in management of Hodgkin's disease.

Ninety-eight patients with clinically localised Hodgkin's disease underwent laparotomy and splenectomy to determine the extent of microscopic spread. In 68 patients the procedure was carried out for untreated disease apparently confined above the diaphragm. Abdominal disease cannot be confidently excluded on the basis of non-invasive investigation at presentation. Clinical assessment of splenic disease was unreliable unless gross splenomegaly was present. Pedal lymphography was accurate in assessing para-aortic and iliac disease but of no value in assessing other intra-abdominal lymph node involvement, including that of the mesenteric lymph node. Trephine bone marrow biopsy findings were normal in all patients before surgery, and only one patient was found to have diseased bone marrow by Stryker-saw biopsy at operation. Liver disease was identified at operation in nine patients, some of whom were asymptomatic with clinically undetectable splenic and nodal disease. Detailed clinical staging failed to detect disease in one-third of patients who underwent laparotomy. These studies show that if radiotherapy is to remain the treatment of choice for disease truly localised to lymph nodes a detailed staging procedure, including laparotomy and splenectomy, remains essential. The value of this potentially curative treatment is considerably diminished in the patient who has been inadequately staged.

Hodgkin Disease↗
PubMed1976

Anti-streptococcal antibodies reacting with brain tissue. II. Utrastructural studies.

The reaction of rabbit anti-Streptococcus pyogenes type 24 with mouse brain has been studied at the ultrastructural level using horseradish peroxidase labelled antiglobulin. It is shown that these antibodies, and by inference those found in Sydenham's chorea, react with the fibrous astrocyte. The cross-reacting antigen is the glial filament or a closely associated cytoplasmic constituent.

Animals↗