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Biomedical subjects

H G Klein

Publications and source records attributed to H G Klein.

At least 73 records · Page 4Linked to original sources
PubMed1993

Plasma exchange does not improve survival in a canine model of human septic shock.

Whether plasma exchange would improve survival in antibiotic-treated canines with septic shock was investigated. Escherichia coli O86H8 (1.4 X 10(10)) was surgically implanted as an intraperitoneal clot in 18 two-year-old (10-12 kg) purpose-bred beagles. Beginning 4 hours after surgery, all animals received cefoxitin and gentamicin for 5 days. Three treatment groups were defined: 1) a no apheresis, or control group, (n = 6); 2) a sham apheresis group, whose whole blood plasma was removed, separated, and then transfused (n = 6); and 3) a plasma exchange group from whom blood and plasma were removed and separated, to whom the blood was returned, and in whom infected plasma was replaced with compatible fresh-frozen canine plasma (n = 6). For the sham apheresis and plasma exchange groups, a commercial blood cell processor was used to separate 1.5 blood volumes of plasma at 5 and 24 hours after surgery. Serial radionuclide left ventricular ejection fractions and femoral and pulmonary arterial catheter hemodynamics were measured simultaneously in awake animals. All six animals in the plasma exchange group died. In both the sham and control groups, only one of six animals survived. Survival times were ordered (median in hours) (control [372 h] > sham apheresis [48 h] > plasma exchange [24 h] [p < 0.038]). Decreases in mean cardiac index and mean arterial pressure (from before apheresis to after) at 5 to 7 hours after surgery were ordered (plasma exchange > sham apheresis > control; p < 0.03). Thus, plasma exchange in this controlled trial of septic shock was associated with decreased survival and worsened hemodynamics.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Fish eye syndrome: a molecular defect in the lecithin-cholesterol acyltransferase (LCAT) gene associated with normal alpha-LCAT-specific activity. Implications for classification and prognosis.

We have identified the molecular defect in two siblings presenting with classical clinical and biochemical features of Fish Eye disease (FED), including corneal opacities, HDL cholesterol < 10 mg/dl, normal plasma cholesteryl esters, and elevated triglycerides. In contrast to previously reported patients with FED who are unable to esterify HDL-associated cholesterol, our patients' plasma lecithin-cholesterol acetyltransferase (alpha-LCAT)-specific activities assayed using an HDL-like proteoliposome substrate were 12.7-25.7 nmol/micrograms (19.5 +/- 1.8 in controls). In addition, significant residual cholesterol esterification was present in VLDL/LDL-depleted plasma, confirming the presence of HDL-associated alpha-LCAT activity. DNA sequence analysis of the proband's LCAT gene identified deletion of the triplet coding for leu300, which resulted in the loss of a restriction site for MlnI. Digestion of PCR-amplified DNA using MlnI established that both siblings are homozygous for this defect. Expression of LCAT300-del. in human embryonic kidney-293 cells revealed normal mRNA and intracellular LCAT concentrations. However, reduced amounts of LCAT300-del., which had a normal specific alpha-LCAT activity, were present in the media. In summary, we report the first case of FED associated with a mutant enzyme that has a normal alpha-LCAT-specific activity. The functional significance of this LCAT gene defect has been established in an in vitro expression system, which demonstrates that very small amounts of this functional LCAT mutant enzyme accumulate in the media. Characterization of LCAT300-del. established that selective alpha-LCAT deficiency is not a prerequisite for the development of FED. On the basis of our combined results, we propose that the residual amounts of total plasma LCAT activity and not its distribution on lipoproteins primarily determines the heterogeneity in phenotypic expression observed in familial LCAT deficiency syndromes.

Base Sequence↗
PubMed1993

Two different allelic mutations in the lecithin:cholesterol acyltransferase (LCAT) gene resulting in classic LCAT deficiency: LCAT (tyr83-->stop) and LCAT (tyr156-->asn).

The molecular defects in the lecithin:cholesterol acyltransferase (LCAT) gene have been identified in a 52-year-old patient with classic LCAT deficiency, presenting with corneal clouding and proteinuria. Plasma total cholesterol was normal, triglycerides were elevated, whereas high density lipoprotein (HDL) cholesterol (8 mg/dl) and plasma cholesteryl esters (6% of total cholesterol) were markedly reduced. Plasma cholesterol esterification rate (pCER) was zero, alpha-LCAT activity, assayed using an HDL-like proteoliposome substrate was reduced to 1.6% of control, and LCAT mass was 3.7% of normal plasma levels. DNA sequence analysis of the proband's LCAT gene identified a C to A substitution, converting tyr83 to a stop codon, and a T to A transition, replacing tyr156 by asn. Restriction analysis of PCR-amplified DNA from the proband, a control and his four children using the enzymes Acc I and Rsa I established that the patient is a compound heterozygote for both mutations. The two children, heterozygous for the stop codon defect, were phenotypically indistinguishable from the two with the tyr156 defect. In vitro expression of LCAT (tyr156-->asn) in human embryonic kidney-293 cells established the functional significance of this mutation. The secreted translation product had only 6% of control mass and no detectable CER; however, the residual LCAT mass of the in vitro expressed LCAT (tyr156-->asn) demonstrated a specific alpha-LCAT activity of 30% of control, suggesting that this amino acid substitution results in a mutant enzyme that retains some enzymic activity, but may be rapidly catabolized. In summary, we have identified two unique defects in the LCAT gene that lead to the expression of classic LCAT deficiency in this kindred.

Alleles↗
PubMed1992

Effect of albumin on the inhibition of platelet aggregation by beta-lactam antibiotics.

Platelet aggregation and bleeding time abnormalities are reported in patients receiving beta-lactam antibiotics (beta LAs), although clinical bleeding most frequently occurs in chronically ill, malnourished patients. Although most beta LAs bind to serum albumin, the relative influence of bound versus unbound beta LAs on platelet function is unknown. We examined the effect of beta LAs on the aggregation of gel-filtered platelets from normal subjects and on platelet-rich plasma (PRP) from hypoalbuminemic patients. Therapeutic concentrations of five beta LAs were added to normal platelets at different albumin concentrations (1.5 to 4.5 g/dL). Inhibition of aggregation by the beta LAs was inversely proportional to the albumin concentration, and most antibiotic-treated samples showed more than 50% inhibition at albumin levels below 2.0 g/dL. When PRPs from hypoalbuminemic patients were incubated with cephalothin, aggregation was completely inhibited, in contrast to samples from patients with normal albumin levels, and this decreased platelet aggregation was partially restored (25% to 75%) by increasing the albumin concentration above 4.0 g/dL. Specific binding of [35S]-benzylpenicillin to normal platelets decreased proportionately as the albumin concentration increased in the range of 1.0 to 5.0 g/dL. The inhibitory effects of beta LAs on platelets in vitro appear to be influenced by albumin concentration. Plasma albumin concentration may influence bleeding in patients receiving beta LAs.

Anti-Bacterial Agents↗
PubMed1992

Epidemiology of thrombocytopenia in HIV infection.

Thrombocytopenia is a known complication of human immunodeficiency virus Type-1 (HIV-1) infection, and more data need to be collected on its frequency, severity, and clinical sequelae. We determined the frequency of thrombocytopenia and its relationship to other HIV infection characteristics from a review of records of 1004 HIV-infected patients attending two outpatient clinics in Washington, D.C. The self-reported sources of HIV-1 exposure were male homosexual activity (68%), bisexual activity (10%), heterosexual activity (6%), and intravenous drug use (15%). Fifty-nine percent of the individuals were white, 37% were black and 94% were male. Fifteen percent had AIDS. Thrombocytopenia occurred more frequently in subjects with AIDS (21.2%) than in HIV-infected individuals who did not fit clinical criteria for AIDS (9.2%) (p less than 0.001). Patients with few CD4-positive cells and an advanced stage of disease were more likely to have low platelet counts: 30% with an absolute CD4 cell count lower than 200/mm3 vs 8% with CD4 counts between 200 and 500 (p less than 0.00001), and 18.5% with Stage IV disease compared to 7.6% in Stage II (p less than 0.001) had platelet counts less than 150,000/mm3. Thrombocytopenia was more frequent in white males and older subjects. Although subjects infected by heterosexual exposure had a lower frequency of thrombocytopenia, intravenous drug users and homosexual men exhibited similar frequencies of thrombocytopenia. Of all subjects with platelet counts less than 50,000/mm3, 40% reported bleeding and 1 died of an intracranial hemorrhage. Thrombocytopenia occurs frequently in HIV-infected people, primarily in those with AIDS, low CD4 cell numbers, and advanced stages of diseases.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Two different allelic mutations in the lecithin-cholesterol acyltransferase gene associated with the fish eye syndrome. Lecithin-cholesterol acyltransferase (Thr123----Ile) and lecithin-cholesterol acyltransferase (Thr347----Met).

We have elucidated the genetic defect in a 66-yr-old patient with fish eye syndrome (FES) presenting with severe corneal opacities and hypoalphalipoproteinemia. The patient's plasma concentration of high density lipoprotein (HDL) cholesterol was reduced at 7.7 mg/dl (35.1-65.3 mg/dl in controls) and the HDL cholesteryl ester content was 31% (60-80% in controls); however, total plasma cholesteryl esters were similar to normal (60% of total cholesterol vs. a mean of 66% in controls). The patient's plasma cholesterol esterification rate was slightly reduced at 51 nmol/ml per h (control subjects: 61-106 nmol/ml per h), whereas lecithin-cholesterol acyltransferase (LCAT) activity, assayed using a HDL-like exogenous proteoliposome substrate, was virtually absent (0.9 nmol/ml per h vs. 25.1-27.9 nmol/ml per h in control subjects). DNA sequence analysis of the proband's LCAT gene revealed two separate C to T transitions resulting in the substitution of Thr123 with Ile and Thr347 with Met. The mutation at codon 347 created a new restriction site for the enzyme Nla III. Analysis of the patient's polymerase chain reaction-amplified DNA containing the region of the Thr347 mutation by digestion with Nla III confirmed that the proband is a compound heterozygote for both defects. The patient's daughter, who is asymptomatic despite a 50% reduction of LCAT activity, is heterozygous for the Thr123----Ile mutation. Our data indicate that the regions adjacent to Thr123 and Thr347 of LCAT may play an important role in HDL cholesterol esterification, suggesting that these regions may contain a portion of the LCAT binding domain(s) for HDL.

Aged↗
PubMed1991

Peripheral blood mononuclear cell collection from patients undergoing adoptive immunotherapy or peripheral blood-derived stem cell transplantation and from healthy donors.

The demand for collection of mononuclear cells from the peripheral blood of patients for therapeutic purposes is rapidly increasing. Automated blood cell separators are usually designed for collection of blood components from healthy donors. We reviewed safety and efficiency of collection data of a new procedure for the Fenwal CS 3000 blood cell separator in 125 collections from normal donors and 101 collections from patients after IL-2 pretreatment or chemotherapy. The new procedure set red blood cell spillovers to occur at 3.5 minute intervals, using procedure 1 with the interface detector set at 1,000 and the standard granulocyte and collection chambers. Despite significant anemia and thrombocytopenia in a large number of patients no serious procedure-related side effects occurred. The lymphocyte yield was 4.74 +/- 1.6 x 10(9) per 5 liters of blood processed in normal donors and 24.2 +/- 12.0 x 10(9) per 10 liters of blood processed after IL-2 treatment. After chemotherapy the lymphocyte yield was 4.5 +/- 3.1 x 10(9) per 10 liters of blood processed; the collection efficiency was found to be significantly lower in this group. The main problem was the platelet loss of 35.6 +/- 12% of the initial count in normal donors, 40.3 +/- 14.1% after IL-2 treatment, and 42.1 +/- 18.0% after chemotherapy. The platelet loss is, however, closely related to the preapheresis platelet count; patients with thrombocytopenia lose fewer platelets than normal donors. Therefore the procedure was found to be safe for patients with a platelet count as low as 20/nl. This report provides a basis for safe, effective mononuclear cell collection from patients with very abnormal peripheral blood counts.

Adolescent↗
PubMed1991

Reduction of platelet glycoprotein Ib in uraemia.

Patients with uraemia have abnormal platelet function that may be partially corrected by haemodialysis, cryoprecipitate or 1-desamino-8-D-arginine vasopressin (DDAVP). We studied the platelet von Willebrand factor receptor, glycoprotein Ib (GPIb), and plasma von Willebrand factor (vWF) in uraemic patients undergoing chronic haemodialysis. Using the slope of agglutination of formalin-fixed platelets as an index of response to ristocetin (with a constant amount of normal plasma as a source of vWF), we found the response of platelets from uraemic patients, both before (2.7 +/- 1.5, n = 40) and after dialysis (1.2 +/- 1.2, n = 40) to be significantly less than that for normal controls (14.1 +/- 10.2, n = 20; P less than 0.001). In addition, the agglutination response of platelets obtained after dialysis was less than that of platelets obtained before dialysis (P less than 0.001). Immunoblotting demonstrated decreased or absent staining of glycocalicin, a subunit of GPIb, in platelet lysates from 25 patients. All platelet samples with reduced glycocalicin also had decreased responses to ristocetin. Tritium-labelled platelets from seven patients showed decreased labelling of a protein with an electrophoretic mobility equivalent to that of GPIb (140,000 daltons). In addition, platelets with the lowest levels of surface GPIb, as demonstrated by flow cytometry, also had decreased ristocetin agglutination and decreased staining on immunoblot. Levels of von Willebrand factor antigen and ristocetin cofactor in plasma from 10 patients were generally within the normal range, although postdialysis levels tended to be higher than pre-dialysis levels. The pre- and post-dialysis plasma vWF multimeric patterns were normal.

Adult↗