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Biomedical subjects

G Kessler

Publications and source records attributed to G Kessler.

At least 19 recordsLinked to original sources
PubMed2000

Comparison and application of a novel genotyping method, semiautomated primer-specific and mispair extension analysis, and four other genotyping assays for detection of hepatitis C virus mixed-genotype infections.

To date the true prevalence of hepatitis C virus (HCV) mixed-genotype infections has not been established mainly because currently available methods are not suitable for the detection of mixed genotypes in a viral population. A novel semiautomated genotyping method, primer-specific and mispair extension analysis (S-PSMEA), which is more reliable than other genotyping assays was developed for detection of HCV mixed-genotype infections. A genotype present at levels as low as 0.8% in a defined mix of HCV genotypes was detected, showing a 20-fold increase in sensitivity over that of direct DNA sequencing. A total of 434 HCV isolates were genotyped and analyzed for a comparative study of the accuracy between S-PSMEA and four current genotyping methods. The results showed that viruses in approximately 40% of the samples from this group determined to be infected with mixed genotypes by S-PSMEA were undetected by direct DNA sequencing due to its low sensitivity. Type-specific PCR, line probe assay, and restriction fragment length polymorphism analysis performed poorly, being able to identify only 38.5, 16.1, and 15.4% of mixed-genotype infections, respectively, that were detected by direct DNA sequencing. The prevalence of mixed-genotype infections detected by S-PSMEA was 7.9% (12 of 152 donors) among HCV-infected blood donors, 14.3% (15 of 105) among patients with chronic hepatitis C, and 17.1% (6 of 36) among thalassemia patients who had received multiple transfusions. The data lead us to conclude that HCV mixed-genotype infections are more common than previously estimated and that S-PSMEA may be the method of choice when detection of genotypes present at low levels in mixed-genotype infections is required due to its higher level of sensitivity.

Base Pair Mismatch↗
PubMed2000

Prevalence of GBV-C/hepatitis G virus viremia and anti-E2 in Canadian blood donors.

BACKGROUND AND OBJECTIVES: GB virus C (GBV-C)/hepatitis G virus (HGV) is a recently recognized parenterally and sexually transmitted agent. The prevalence of GBV-C/HGV markers in Canadian blood donors has not been previously studied and was therefore determined. MATERIALS AND METHODS: Blood donors [identity unlinked (IU), short-term temporarily deferred (STTD) and autologous groups] and donor samples with antibodies to hepatitis C (anti-HCV) or hepatitis B core were tested for GBV-C/HGV RNA and for antibodies to E2 antigen (anti-E2). RESULTS: GBV-C/HGV RNA was found in 1.1% and anti-E2 in 7.3% of the combined IU/STTD donor group. Viremia was much more common in anti-HCV-positive samples (12.5%); anti-E2 was present in >50% of this group. In the STTD group, female gender was significantly associated with viremia. CONCLUSION: GBV-C/HGV infection is relatively common in Canadian donors, and a small proportion are viremic. The association of female gender and viremia was unexpected. Further study is needed to clarify the epidemiology and natural history of GBV-C/HGV infection.

Adolescent↗
PubMed2000

Lipid peroxidation and the expressional regulation of the heat-shock response during ischemia-reperfusion of rat kidney.

Because of the continuing shortage of donor organs, 'marginal kidneys' are increasingly being used. The purpose of our experiments was to characterize the extent of lipid peroxidation after ischemia-reperfusion (IR) injury in rat kidney, to analyze the expressional regulation of the heat-shock response and now to discuss the clinical application of these results. After ischemia, xanthine oxidase (XO) is thought to be the main oxygen radical-generating system and malondialdehyde (MDA) is considered to be a marker of LPO. In young rats (10 weeks) a unilateral warm ischemia of 40 and 60 min duration with subsequent reperfusion up to 1 h was conducted. Beside the 'footprints' of oxidative stress, the cytosolic antioxidative capacity, expressed as superoxide anion (SOA) scavenging capacity, was investigated. There was only a moderate and transient increase of renal MDA 5 and 10 min after the onset of reoxygenation (133.57/70.67 and 97.84/91.57 vs. 49.47 nmol/g wet weight (ww) in preischemic controls). ATP breakdown (to 83/65 from 2,947 nmol/g ww) with consecutive accumulation of hypoxanthine (up to 1,105 nmol/g ww) at the end of the ischemic period and the subsequent rapid decline of hypoxanthine by XO during reperfusion were used for an assessment of the SOA-generating capacity of these kidneys. Only 1/25-1/50 of the kidney cytosol was able to scavenge the whole amount of SOA generated by the total XO activity of rat kidney. Thus, it could be analytically and stoichiometrically shown that after IR there is only a moderate oxidative stress in kidneys of young rats; this is due to their high SOA-scavenging capacity compared to their SOA-generating ability. We investigated the time course of HSP70-1 and -2 mRNA expression and its relation to cellular ATP levels in renal cortex after different periods of unilateral warm renal ischemia (10-60 min) and reperfusion (up to 60 min) in 10-week-old male Wistar rats, since IR is known to cause induction of both genes. Immediately after ischemia there was a significant induction of both HSP70i genes. While HSP70-1 expression constantly increased (up to 4-fold) during reperfusion, even to a higher extent with prolongation of ischemia, HSP70-2 mRNA - generally being expressed on a far lower level than HSP70-1 mRNA - was strongly induced (3-fold) during reperfusion only after brief periods (10 min) of ischemia. Cellular ATP levels rapidly dropped down to 5% with ischemia and the pattern of recovery during reperfusion significantly depended on the duration of the ischemic period thus showing a good relation to the heat-shock (protein) gene expression. We conclude that the HSP70-2 is the more sensitive gene with a lower threshold activation by mild injury, while the HSP70-1 gene mediates the big response of HSP induction after severe injury. Thus, the measurement of the cytosolic antioxidative capacity and the differential expression of HSP70-1 and -2 mRNA could be promising clinical tools to assess the donor viability.

Adenosine Triphosphate↗
PubMed1999

No association between hepatitis C and B-cell lymphoma.

Chronic viral infection has been implicated in the pathogenesis of B-cell lymphoma, and hepatitis C virus (HCV) infects lymphocytes. Chronic infection with HCV may result in B-cell proliferation. Individuals infected with hepatitis C are often co-infected with the RNA virus GB virus type C. Studies from Europe where hepatitis C infection is more common than in North America have shown a high prevalence of hepatitis C infection in patients with B-cell lymphoma. The aim of this study was to establish the prevalence of HCV and GBV-C infection in patients with B-cell lymphoma in an area of low HCV prevalence. One hundred patients with B-cell lymphoma (10 high grade, 46 intermediate grade, and 44 low grade) and 100 controls with nonhematological malignancies were studied. Serum was analyzed for HCV antibodies by third generation enzyme-linked immunosorbant assay, and HCV RNA and GBV-C RNA was analyzed by reverse transcriptase PCR. None of the controls or lymphoma patients had antibodies to HCV. HCV RNA was undetected in 60 out of 100 lymphoma patients tested. GBV-C RNA was detected in the serum of 5 out of 100 (5%) of lymphoma patients and in 3 out of 100 (3%) controls. Hepatitis C and GBV-C are, therefore, unlikely to play a major role in the pathogenesis of B-cell lymphoma in North America.

Antibodies, Viral↗
PubMed1999

Evidence for only a moderate lipid peroxidation during ischemia-reperfusion of rat kidney due to its high antioxidative capacity.

The extent of lipid peroxidation after ischemia-reperfusion (I-R) injury in rat kidney has been controversial. After I, xanthine oxidase (XO) is thought to be the main oxygen radical-generating system and malondialdehyde (MDA) is considered to be a marker of lipid peroxidation (LPO). In young rats (10 weeks old) a unilateral warm I of 40 and 60 min duration with subsequent R up to 1 h was conducted. Beside the "footprints" of oxidative stress, the cytosolic antioxidative capacity, expressed as superoxide anion (SOA) scavenging capacity, and the renal catalase were also investigated. There was only a moderate and transient increase of renal MDA 5 and 10 min after the onset of reoxygenation (133.57/70. 67 and 97.84/91.57 vs. 49.47 nmol/g ww in preischemic controls). ATP breakdown (to 83/65 from 2947 nmol/g ww) with consecutive accumulation of hypoxanthine (up to 1105 nmol/g ww) at the end of ischemic period and the subsequent rapid decline of hypoxanthine by XO during reperfusion were used for an assessment of the SOA-generating capacity of these kidneys. Superoxide dismutase (SOD) activity, glutathione (GSH) and the high activity of catalase (18000 U/g ww) remained nearly unchanged during R. Only 1/25-1/50 of the kidney cytosol was able to scavenge the whole amount of SOA generated by the total XO activity of rat kidney. Thus, it could be analytically and stoichiometrically shown that after IR there is only a moderate oxidative stress in kidneys of young rats; this is due to their high SOA-scavenging capacity compared with their SOA-generating ability.

Adenosine Triphosphate↗
PubMed1998

Primer specific and mispair extension analysis (PSMEA) as a simple approach to fast genotyping.

A simple method, primer specific and mispair extension analysis (PSMEA) with pfu DNA polymerase was developed for genotyping. PSMEA is based on the unique properties of 3'-->5' exonuclease proofreading activity. In the presence of an incomplete set of dNTPs, pfu was found to be extremely discriminative in nucleotide incorporation and proofreading at the initiation step of DNA synthesis, completely preventing primer extension when mispair(s) are found adjacent to the 3'-end of the primer. This has allowed us to accurately detect nucleotide variations, deletions and insertions for fast genotyping.

Base Pair Mismatch↗
PubMed1997

[Life-threatening swelling of the tongue in antihypertensive therapy with ACE inhibitors].

Although generally showing a low incidence of side effects, inhibitors of angiotensin-converting enzyme (ACE) may in rare cases induce angioedemas, mainly located in the oro-facial area and larynx. The interval between the beginning of the ACE inhibitor therapy and the occurrence of such angioedemas may range from a few hours to a few years. Here, the case of a 53-year-old man with massive swelling of the tongue after dental surgery is presented who had started with ACE inhibitor therapy only 24 h before. At admission to the clinic, obstruction of the upper airway due to the tongue swelling had already progressed so far that fiberoptic intubation was necessary. Additionally, the patient was treated with corticosteroids, antihistaminics and epinephrine, avoiding any further administration of the ACE inhibitor. The swelling resolved within 48-72 h. Dentists and physicians should take into consideration this potential side effect in patients treated with ACE inhibitors.

Angioedema↗
PubMed1997

Comparison of continuous spinal with combined spinal-epidural anesthesia using plain bupivacaine 0.5% in trauma patients.

We investigated the efficacy and complications of microcatheter spinal anesthesia (CSA) in comparison to a combined spinal-epidural technique (CSE) using plain bupivacaine 0.5%. Sixty trauma patients randomly received either CSA using a 22-gauge Sprotte needle and a 28-gauge microcatheter or CSE after insertion of a 22-gauge epidural catheter through an 18-gauge Tuohy needle followed by dural puncture with a 25-gauge pencil-point needle inserted through the backeye of the Tuohy needle. An initial subarachnoid bolus of 2 mL of plain bupivacaine 0.5% was injected. If analgesia did not reach T12 within 20 min, supplemental bupivacaine was injected either intrathecally or epidurally up to a maximum of 5 mL in the CSA group or 16 mL in the CSE group. Mean arterial blood pressure, heart rate, and analgesic levels were recorded. On postoperative Day 4, patients were interviewed for postanesthetic complaints. Technical problems were more frequent in the CSE group than in the CSA group (47% vs 13%). Performance of anesthesia was faster (8 +/- 3 vs 15 +/- 8 min) and the total dose of bupivacaine lower (3.2 +/- 1.0 vs 9.7 +/- 5 mL) in patients who received CSA. The incidence of hypotension did not differ significantly. However, more patients in the CSE group were treated for bradycardia (4 vs 0). The number of patients suffering from postdural puncture headache was comparable in both groups, but there were more patients with lower back pain in the CSE group (8 vs 2). In conclusion, our data suggest that microcatheter CSA is not associated with an increased rate of complication in patients with lower limb fractures.

Adult↗
PubMed1991

Influence of assay method differences on multiple of the median distributions: maternal serum alpha-fetoprotein as an example.

A straightforward statistical explanation is provided to show how differences between assay methods can affect the distribution of the multiples of the median (MoM). Evaluation of the impact of assay method differences reveals that the upper tails of the MoM distribution are not affected to the same degree as the lower tails of the distribution. The disparities in MoM distributions due to assay method differences result in various sensitivity/specificity combinations for different assays having the same fixed MoM cutoffs. Disparities do not exist if risks are calculated with use of the distributions for affected and unaffected populations that are based on a center's own assay method. Applying published risk tables, however, can affect the accuracy of the risk estimates. We used maternal serum alpha-fetoprotein as an example of an assay with an established history of reporting results in MoM values; however, the concepts presented apply equally well to any assay for which results are reported in MoMs.

Female↗