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Biomedical subjects

D F Birch

Publications and source records attributed to D F Birch.

10 recordsLinked to original sources
PubMed1991

Survival of Gardnerella vaginalis in human urine.

The authors studied the survival of Gardnerella vaginalis in human urine and determined conditions for optimum recovery on agar media. Gardnerella counts declined by greater than 99.9% in urine held at 37 degrees C for 24 hours, whereas the falloff was negligible at 4 degrees C. Viability was lost after 6 hours in urine with pH of 5, and only 0.01% cells survived in urine with pH of 7. In contrast, greater than 90% cells survived exposure at pH of 6. Dialysis to remove small molecular weight (less than 14,000) inhibitors did not enhance survival. Co-cultivation with Ureaplasma urealyticum and the addition of glycogen improved survival. Maximum recovery from urine required anaerobic incubation on enriched agar medium (pH 6.5-7.5) for at least 48 hours. Gardnerella vaginalis survives poorly in human urine at 37 degrees C. Culture for these bacteria requires prolonged anaerobic incubation.

Agar↗
PubMed1991

Sterile pyuria.

Explore the source record for details and available documents.

Bacteria↗
PubMed1990

Biochemical and histologic findings in experimental pyelonephritis due to Ureaplasma urealyticum.

Ureaplasma urealyticum has previously been shown to be capable of persisting in the rat kidney for up to 6 months following a single reflux challenge. We examined kidney tissue from infected animals for evidence of renal damage by using standard cytochemical and immunoenzyme methods. We also monitored changes in renal function during a 6-month study period with standard biochemical assays of plasma and urine. Histologic examination showed tubular atrophy, interstitial fibrosis, and a mononuclear infiltrate in proportion to ureaplasma counts from renal tissue. The most severe damage was accompanied by hyaline cast formation within tubules which gave rise to the typical thyroidlike appearance of chronic pyelonephritis involving conventional urinary pathogens. Macroscopic renal scarring occurred in some animals. Although damage to the renal medulla was moderate to severe, only minor changes were seen in the cortex, and glomeruli were invariably spared. Biochemical tests of renal function showed similar changes in infected and uninfected animals during the study period. Interstitial inflammation was characterized by a mononuclear cell infiltrate in which polymorphonuclear leukocytes were not conspicuous. It is evident that U. urealyticum is capable of producing chronic pyelonephritis in the rat after a single reflux challenge. The results of this study have obvious implications for the pathogenicity of these bacteria in human pyelonephritis.

Animals↗
PubMed1989

Urine cytologic profile in renal allograft recipients determined by monoclonal antibodies. Diagnosis of allograft rejection.

Controversy exists as to the type of cells present in the urine during renal allograft rejection. In order to resolve this controversy as well as to evaluate the value of urine sediment examination as a means of detecting AR, we quantitated the different cells present in urine during AR using an immunoperoxidase technique and monoclonal antibodies reactive with lymphocytes, monocytes, granulocytes, glomerular epithelial, tubular, and urothelial cells. Urine sediment (n = 176) was examined serially over 3 months in 15 transplant recipients. There were 12 episodes of early posttransplant acute tubular necrosis and 21 episodes of AR. It was possible to detect AR as well as to distinguish AR from ATN. Lymphocyte and tubular cell excretions were increased significantly during AR. Excretion of urothelial cells was also significantly increased during most episodes of AR suggesting that rejection of ureters occurs concomitantly with rejection of the kidneys.

Antibodies, Monoclonal↗
PubMed1989

Immunoperoxidase identification of nucleated cells in urine in glomerular and acute tubular disorders.

Nucleated nonsquamous cells in urine of patients with crescentic glomerulonephritis (CN), noncrescentic glomerulonephritis (NCN), acute tubular necrosis (ATN) and drug related acute interstitial nephritis (AIN) were identified using monoclonal antibodies and immunoperoxidase stain. Cell viability was determined by trypan blue permeability. CN was distinguishable from NCN by total cell numbers exceeding 30,000/ml (p less than 0.001) and counts of granulocytes exceeding 10,000/ml (p less than 0.05), monocytes exceeding 3,000/ml (p less than 0.001), T4 lymphocytes exceeding 1,500/ml (p less than 0.001), T8 lymphocytes exceeding 1,500/ml (p less than 0.001), glomerular epithelial cells exceeding 4,000/ml (p less than 0.001), proximal tubular cells exceeding 8,000/ml (p less than 0.001), loop of Henle cells exceeding 1,500/ml (p less than 0.01) and urothelial cells exceeding 1,500/ml (p less than 0.05). AIN was distinguishable from ATN by total cell numbers exceeding 75,000/ml (p less than 0.001) and counts of granulocytes exceeding 150,000/ml (p less than 0.001), monocytes exceeding 5000/ml (p less than 0.001), T4 lymphocytes exceeding 3,000/ml (p less than 0.01), T8 lymphocytes exceeding 2,500/ml (p less than 0.01) and cell viability exceeding 60% (p less than 0.05). Proximal tubular, loop of Henle, distal tubular/collecting duct and urothelial cells were present in high numbers in CN, ATN and AIN. CN can be distinguished from NCN, and ATN can be distinguished from AIN by identifying and quantifying the nucleated cells present in the urine.

Acute Kidney Injury↗
PubMed1978

Persistent bacteriuria in the rat after reflux challenge with Pseudomonas aeruginosa.

An experiment based upon reflux of culture suspensions of Pseudomonas aeruginosa into the rat kidney was set up to examine possible factors of importance in the development of ascending renal infection. We monitored the persistence of challenge bacteria in the rat urinary tract by quantitative culture of urine collected by spontaneous micturition, despite heavy contamination with commensal microflora. In most animals challenged, pseudomonads gave rise to bacteriuria of only limited duration. During bacterial persistence in urine, colony counts fluctuated widely from day to day.

Animals↗
PubMed1978

Renal infection in the rat after reflux challenge with Pseudomonas aeruginosa.

A rat-pseudomonad reflux model was employed to examine the effect of the size of inoculum on the emergence of renal infection. Widely varying degrees of renal disease observed in challenged animals indicated that a number of variables influenced the outcome of the host-parasite interaction. In this regard, animals in which there was a reduction of the colony counts below a threshold figure rarely gave evidence of renal infection when examined at autopsy on the eighth day following reflux. These results suggest that a threshold level of bacteriuria may also have to be exceeded if renal infection is to become established in patients with vesico-ureteric reflux.

Animals↗