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Biomedical subjects

J P Kavanagh

Publications and source records attributed to J P Kavanagh.

18 recordsLinked to original sources
PubMed1992

Pyrophosphate in synovial fluid and urine and its relationship to urinary risk factors for stone disease.

Inorganic pyrophosphate (PPi) measurement in urine and synovial fluid has been established using the PPi-dependent phosphorylation of fructose-6-phosphate and subsequent reduction of dihydroxyacetone phosphate by NADH. The assay is linear up to 200 mumol/L, easy to perform and gives results comparable to more complex methods. Daily urinary output of PPi was independently related to both age (P = 0.0014) and sex (P = 0.0002). Men had higher values than women and older individuals excreted greater amounts. Male stone formers, younger than 45 years, had lower values than age matched male controls (P = 0.012). Younger female stone formers also tended to have lower values. In stone formers' urine significant and independent correlations were found of PPi excretion with urine volume (P = 0.004) and with phosphate excretion (P = 0.008). Oxalate excretion and that of other urine constituents and the degree of supersaturation with common stone-forming salts were not correlated with PPi. PPi excretion was markedly elevated in the urine of two patients with hypophosphatasia. The PPi concentration in synovial fluid from painful, swollen knee joints was elevated, but unrelated to the presence or absence of PPi or urate crystals.

Adolescent↗
PubMed1992

Methods for the study of calcium oxalate crystallisation and their application to urolithiasis research.

Many methods have been used to study calcium oxalate crystallisation. Most can be characterised by changes in supersaturation during the experiment, which may increase, remain constant or decay. Their ability to quantify various aspects of crystallisation often reflects the extent to which nucleation, growth and aggregation can be measured independently, when two or three of these processes may be occurring simultaneously. The mixed suspension, mixed product removal technique reaches a steady state supersaturation, is a good model for intrarenal crystallisation and allows both growth and nucleation rates to be measured. Using 92% urine and comparing control urines with samples from recurrent stone formers no difference in growth rates was found but the controls had higher nucleation rates (p = 0.003) and lower supersaturations (p = 0.001). In parallel crystallisers running simultaneously, heparin or hyaluronic acid addition to 92% urine was studied. Both macromolecules increased growth rates, decreased nucleation rates and increased supersaturation (p < 0.05). The steady state supersaturation achieved in this system may be an important determinant of stone forming potential. The ability to reach a lower urinary supersaturation by increased nucleation may be a crucial protective factor distinguishing non stone formers from stone formers.

Calcium Oxalate↗
PubMed1990

Do stone formers have lower urinary fibrinolytic activity than controls?

A comparison of urinary fibrinolytic activity between 31 stone formers and 50 controls failed to demonstrate any significant difference and so failed to confirm an earlier independent observation. This may be due to methodological and design differences between the 2 studies, but does suggest reservations about the significance of lowered urinary fibrinolytic activity as a risk factor for renal stone disease. Dietary information from those taking part in the study suggests that a reduction of meat intake by stone formers might be associated with increased urinary fibrinolytic activity. This might account for the discrepancy between the 2 studies, in which case this observation could be of significance.

Creatinine↗
PubMed1990

Calcium oxalate crystallisation kinetics and the effects of calcium and gamma-carboxyglutamic acid.

gamma-carboxyglutamic acid (GLA) is an amino acid with a high affinity for calcium. It is found in urine both as the free amino acid and incorporated into proteins such as osteocalcin. Free and bound GLA have been reported to be found at higher concentrations in the urine of stone formers than controls. We have investigated the effect of GLA and calcium, at physiological levels, on the crystallisation of calcium oxalate using a mixed suspension mixed product removal continuous crystalliser. GLA caused very significant changes in the crystallisation kinetics, but the effect was dependent on the calcium concentration. At 4 mM calcium, GLA decreased the growth rate and increased the nucleation rate; at 12 mM the reverse occurred. At all concentrations of calcium tested, GLA caused a significantly increased crystal mass to be produced. Our evidence supports the hypothesis that GLA modifies calcium oxalate crystallisation and could be a promoter of stone formation in vivo, particularly at moderately elevated levels of calcium excretion.

1-Carboxyglutamic Acid↗
PubMed1988

Ratio of post-prostatic massage urinary zinc concentration to initial urinary zinc concentration. An improved method of assessing prostatic function.

Various methods have been used clinically to assess prostatic function. We evaluated a number of ways of using zinc in post-prostatic massage urine (VB3) and found that the ratio of VB3 zinc concentration to initial urinary zinc concentration was a good indicator of prostatic secretory activity. This ratio can differentiate hormonally treated patients with carcinoma of the prostate from those untreated and from those with benign prostatic hypertrophy. The specificity is increased for individuals by repeat samples. Comparison of samples before and after resection showed no loss of function and no difference was found between groups treated with orchiectomy or LHRH agonist (Zoladex). The VB3/VB1 zinc concentration could be used in a prospective study of hormonal treatments directed against the prostate, where it could give objective evidence of a fall in secretory function of the gland.

Humans↗
PubMed1986

Urogastrone-epidermal growth factor concentrations in prostatic fluid of normal individuals and patients with benign prostatic hypertrophy.

High concentrations (272 +/- 33 ng/ml) of urogastrone-epidermal growth factor were measured in prostatic fluid from normal males by a specific radioimmunoassay. Significantly lower concentrations (155 +/- 24 ng/ml) were observed in the prostatic fluid of patients with benign prostatic hypertrophy than in the age-matched normal controls (2P less than 0.01). The growth factor content of seminal fluid was accounted for by the contribution of prostatic fluid. Immunochemical studies failed to show evidence of synthesis within the gland nor could high affinity receptors for the protein be demonstrated in membrane preparations of the gland.

Chromatography, Gel↗
PubMed1986

Does sucrose damage kidneys?

There is evidence to suggest that sucrose ingestion can cause renal parenchymal changes as well as increasing the urinary saturation index for calcium oxalate. Ten stone formers and 10 normal subjects received 250 gm of sucrose daily over a period of 7 days. Observations on the risk factors for calcium stone formation and urinary N-acetyl-B-glucosaminidase (NAG), a marker of renal tubular cell damage, were made. Oxalate excretion increased. Urinary calcium levels were unchanged but the pattern of response was different between the two groups, as with magnesium and phosphate. NAG was spontaneously higher in the patient group and increased significantly after sucrose ingestion in both groups.

Acetylglucosaminidase↗
PubMed1985

Sodium, potassium, calcium, magnesium, zinc, citrate and chloride content of human prostatic and seminal fluid.

The ionic composition of human prostatic fluid varied greatly between individuals, reflecting the secretory activity of the gland and the presence or absence of prostatic inflammatory disease. In normal prostatic fluid the major anion was citrate, while chloride concentrations were lower. Their counterions were mainly sodium and potassium, together with calcium, magnesium and zinc. Prostatic secretions from men with prostatitis comprised mainly sodium and chloride. The electrolytes were closely correlated to each other (except for sodium, which was essentially invariant at about 145 nm). The molar changes per mole of citrate were about 0.52, potassium; -0.53, chloride; 0.17, calcium; 0.14, magnesium; and 0.09, zinc. The pH was also associated with citrate, decreasing from 8.0 to 6.2 as the citrate increased. These various ionic changes can be explained as responses to citrate secretion, without the need to propose specific transport mechanisms for the other ions measured. The marked effect of prostatic inflammation on the composition of prostatic fluid can be seen as being due mainly to decreased secretion rather than active modification.

Calcium↗
PubMed1983

Zinc in post prostatic massage (VB3) urine samples: a marker of prostatic secretory function and indicator of bacterial infection.

The value of biochemical examination of post-prostatic massage (VB3) urine samples has been investigated. Measurement of zinc levels provides a good marker of prostatic secretory function. In the absence of prostatic carcinoma findings of greater or equal to 100 micrograms zinc in VB3 urines is strong evidence (2% false negatives) of an absence of infectious or inflammatory prostatic disease. Less than 40 micrograms of zinc is suggestive (14% false positives) of prostatitis. There is little need to consider the endogenous urinary zinc levels. This simple test should be of particular value in cases where an expressed prostatic secretion is not obtained (about 40% of this series of patients), when it would be a valuable adjunct to cytological and bacteriological examination of split urine samples.

Bacterial Infections↗
PubMed1983

Creatine kinase and ATPase in human seminal fluid and prostatic fluid.

A creatine kinase assay based on estimation of creatine liberated from creatine phosphate was accurate and reproducible for use with seminal or prostatic fluid, after allowance was made for acid phosphatase interference. Comparison of this method with one which relies on enzymic coupling of ATP formation to NADP+ oxidation shows that the latter under-estimates creatine kinase activity by a factor of about 3. This discrepancy could be due to the high ATPase activity found in prostatic and seminal fluid. Uncritical use of the NADP+ assay might account for different seminal creatine kinase values reported in the literature. Interrelationships between ATPase, creatine kinase and zinc suggest that seminal ATPase is a prostatic secretory product while creatine kinase may be multiglandular in origin.

Adenosine Triphosphatases↗
PubMed1983

Zinc binding properties of human prostatic tissue, prostatic secretion and seminal fluid.

When studied by gel filtration, zinc in prostatic cytosol (10(5) g, 1 h) was associated with high (greater than 80000), medium (3000-80000) and low molecular weight (less than 3000) molecules in approximately equal proportions. The molecules of high and medium Mr were not secreted into the prostatic fluid where all the zinc was associated with molecules of low Mr (probably citric acid). After ejaculation much of the zinc is redistributed and becomes bound to molecules of high and medium Mr of vesicular origin.

Body Fluids↗
PubMed1982

The interrelationships between acid phosphatase, aminopeptidase, diamine oxidase, citric acid, beta-glucuronidase, pH and zinc in human prostatic fluid.

Biochemical analysis of 328 human prostatic fluid samples were performed. The urea concentration of 69 samples was similar to that of serum and not indicative of significant contamination with urine. The pH of normal fluids was acidic (mean pH = 6.7). The interrelationships between zinc, citrate, acid phosphatase aminopeptidase, beta-glucuronidase, diamine oxidase and pH were investigated by factor analysis. Two significant factors were extracted, the first accounted for 89% of their common variance and the second for 11%. Zinc, citrate, acid phosphatase and aminopeptidase were positively and pH was negatively related to factor one. Beta-glucuronidase was positively related to factor two and diamine oxidase was largely independent of both factors. It was concluded that variables related to factor one share a common secretory control and mechanism, that some other mechanism operates in the case of beta-glucuronidase and that diamine oxidase may not be a true secretory product of the prostate.

Acid Phosphatase↗
PubMed1981

Levamisole and other diamine oxidase inhibitors as inhibitors of sperm motility.

Levamisole, an anthelmintic drug and inhibitor of sperm motility, is a potent inhibitor of seminal diamine oxidase. Many other diamine oxidase inhibitors also inhibit sperm motility. The most active class of these sperm motility inhibitors is the group for isothiuronium compounds, some of which are much more potent than many other metabolic inhibitors tested. They also possess the property of inducing sperm to be motile in closed circles becoming immotile with a characteristically curled shape, and are active against mouse epididymal, rabbit, and human spermatozoa.

Amine Oxidase (Copper-Containing)↗
PubMed1979

The identity of the acid and alkaline phosphatases of human seminal plasma.

Examination of human seminal plasma showed that there was no p-nitrophenylphosphatase activity maximum at alkaline pH values. A constant ratio of enzyme activities in 8 split ejaculates, identical temperature dependence and copurification through a three-step purification procedure led us to conclude that the alkaline phosphatase in human semen is identical to acid phosphatase.

Acid Phosphatase↗