Road blocks in making platelets for transfusion.

The production of laboratory-generated human platelets is necessary to meet present and future transfusion needs. This manuscript will identify and define the major roadblocks that must be overcome to make human platelet production possible for clinical use, and propose solutions necessary to accelerate development of laboratory-generated human platelets to market.

In vitro inactivation of Chlamydia trachomatis by fatty acids and monoglycerides.

The antichlamydial effects of several fatty acids and monoglycerides were studied by incubating Chlamydia trachomatis bacteria with equal volumes of lipid solutions for 10 min and measuring the reduction in infectivity titer compared with that in a control solution without lipid. Caprylic acid (8:0), monocaprylin (8:0), monolaurin (12:0), myristic acid (14:0), palmitoleic acid (16:1), monopalmitolein (16:1), oleic acid (18:1), and monoolein (18:1) at concentrations of 20 mM (final concentration, 10 mM) had negligible effects on C. trachomatis. In contrast, lauric acid (12:0), capric acid (10:0), and monocaprin (10:0) caused a greater than 10,000-fold (>4-log10) reduction in the infectivity titer. When the fatty acids and monoglycerides were further compared at lower concentrations and with shorter exposure times, lauric acid was more active than capric acid and monocaprin was the most active, causing a greater than 100, 000-fold (>5-log10) inactivation of C. trachomatis at a concentration of 5 mM for 5 min. The high levels of activity of capric and lauric acids and particularly that of monocaprin are notable and suggest that these lipids have specific antichlamydial effects. The mode of action of monocaprin was further studied by removal of the lipid by centrifugation before inoculation of Chlamydia onto host cells and by electron microscopy. The results indicate that the bacteria are killed by the lipid, possibly by disrupting the membrane(s) of the elementary bodies. A 50% effective concentration of 30 microgram/ml was found by incubation of Chlamydia with monocaprin for 2 h. The rapid inactivation of large numbers of C. trachomatis organisms by monocaprin suggests that it may be useful as a microbicidal agent for the prevention of the sexual transmission of C. trachomatis.

Comparison of Roche Cobas Amplicor and Abbott LCx for the rapid detection of Chlamydia trachomatis in specimens from high-risk patients.

OBJECTIVE: To evaluate two automated amplification systems for the detection of Chlamydia trachomatis in urogenital specimens, the Cobas Amplicor (Roche Diagnostic Systems, Branchburg, NJ) and the LCx (Abbott Laboratories, Abbott Park, IL). STUDY DESIGN: The two systems were compared testing specimens from 302 high-risk patients, including 98 female cervical swab specimens and 204 male urine specimens. The patients attended the state STD clinic in Reykjavik, Iceland, either because of symptoms or as a result of contract tracing. RESULTS: The prevalence of C. trachomatis infection was 15.3% in women and 13.2% in men. For the male urine specimens, the sensitivity and specificity were 100% and 99.4% for the Cobas Amplicor and 74.1% and 100% for the LCx. In the cervical swabs, both systems detected all 15 true-positive specimens. The internal control used with the Cobas Amplicor detected inhibition in 2% of the male urine and 20% female cervical swabs, respectively. CONCLUSION: The Cobas Amplicor demonstrated slightly better sensitivity than LCx in male urine specimens. Both systems offer the benefits of automation for routine diagnostic testing.

Diagnosis of Chlamydia trachomatis infection in high-risk females with PCR on first void urine.

Recently the polymerase chain reaction (PCR) has been shown to be more sensitive than older methods in detecting Chlamydia trachomatis, when performed on endocervical swabs. A total of 203 high-risk females were enrolled in a comparative study of 3 methods for diagnosing C. trachomatis infections: McCoy cell culture and Amplicor PCR on endocervical swabs, and urine. Thirty-four had positive cultures, 38 positive PCR from cervix and 37 had positive PCR on urine specimens. When discrepancy occurred, the leftover Amplicor specimen was retested by Roche with Amplicor and a primer for the major outer membrane protein (MOMP) gene. In all three tests, 32 were positive. The sensitivity of culture was 87%, 92% in cervical PCR and 95% in urinary PCR. The specificity was 100% in both culture and urinary PCR but 98% in cervical PCR. Amplicor PCR performed on female urine is at least as sensitive and specific as cell culture.

[Diagnosis of chlamydia trachomatis infections in women: urinary PCR compared to cervical culture and PCR on cervical swabs in high risk females.].

Diagnosis of Chlamydia trachomatis infections in women has traditionally depended on cell culture or enzyme linked immunoassay. Recently Polymerase Chain Reaction (PCR) has been shown to be more sensitive than these methods when performed on endocervical swabs. A total of 203 high risk females were enrolled in a comparative study of three methods for diagnosing C. trachomatis infections: McCoy cell culture and Amplicor(R) PCR on endocervical swabs and urine. Thirty four had positive cultures, 38 positive PCR from cervix and 37 had positive PCR on urine specimens. When discrepancy occurred, the leftover Amplicor(R) specimen was retested by Roche with Amplicor(R) and a primer for the Major Outer Membrane Protein (MOMP) gene. None was false positive in cell culture or in urinary PCR but two were false positive in cervical PCR. In all three tests, 32 were positive. The sensitivity of culture was 87%, 92% in cervical PCR and 95% in urinary PCR. The specificity was 100% in both culture and urinary PCR but 98% in cervical PCR. The results show that Amplicor(R) PCR performed on female urine is more sensitive and as specific as cell culture.

[Clinical evaluation of a rapid polymerase chain reaction (PCR) assay: for the detection of chlamydia trachomatis in specimens from high risk patients.].

A Rapid Polymerase Chain Reaction Assay (Ampli-cor(R)-PCR) was evaluated for the detection of Chlamydia trachomatis in specimens from 179 high risk patients. The results were compared to McCoy cell culture and specimens were retested with Amplicor(R) and primers for the Major Outer Membrane Protein (MOMP) gene when discrepancy occurred. Of 88 females enrolled in the study, 30 were infected (34%). Sensitivity, selectivity, predictive value of a positive (PVP) and a negative (PVN) on endocervical specimens were 97%, 96.5%, 96.5% and 98% respectively. Of 91 male urine specimens, 33 (36%) came from infected patients. The sensitivity and specificity of the Amplicor(R) assay was 94% and 74% respectively for male urine specimens and the PVP and PVN were 72% and 96% respectively. The sensitivity was low on the original run on urethral specimens but the majority of false negative specimens became positive when retested. Amplicor(R) performed on urine samples was the most sensitive test for detecting Chlamydial infections in males.

[Clinical evaluation of two immunoassay methods for the rapid detection of chlamydia trachomatis: antigen in endocervical specimens from high risk female patients.].

Two rapid immunoassay methods, QuickVue-Chlamydia (Quidel Corp., San Diego California) and Kodak Surecell (Kodak Corp. Rochester, N.Y.) were evaluated for the detection of Chlamydia trachomatis antigen in endocervical swabs from high risk females attending a sexually transmitted disease clinic. The results were compared to McCoy cell culture and a polymerase chain reaction assay (Amplicor(R)-PCR, Roche Molecular Systems). Of the 240 females enrolled in the study 45 were considered infected (18.8%). Sensitivity, specificity, predictive value of a positive (PVP) and predictive value of a negative (PVN) of the QuickVue-Chlamydia assay were 96%, 99%, 96% and 99% respectively. Sensitivity, specificity, PVP and PVN of the Surecell assay were 96%, 100%, 100% and 99% respectively. The performance of the two immunoassay methods was similar, the sensitivity was the same and the specificity of the Kodak Surecell was slightly better than that of the QuickVue. On the other hand, the QuickWVL-Chlamydia assay was considerably simpler to perform (fewer steps) than the Kodak Surecell assay and took significantly less of technologists time.

[Prevalence of genital chlamydia trachomatis infections in college students.].

UNLABELLED: Sexually transmitted Chlamydia infection is the most common venereal disease in Iceland. Although considerable information is available on the epidemiology of these infections, the true prevalence of C. trachomatis infections in Iceland is unknown because all the studies have been conducted on selected populations. The purpose of the present study was twofold: To investigate the prevalence of Chlamydia infection in an unselected group of people in the age group at high risk, and to investigate the usefulness of collecting urine samples from college students as a screening method for Chlamydia. All students, aged 18-21, in the senior classes in a college in Reykjavik were requested to submit a first void urine (FVU) specimen taken in the morning and asked to fill out a short questionnaire. The urine samples were tested with a polymerase chain reaction assay, the Amplicor(R) PCR. One hundred eighty three students received urine collection kits. One hundred sixty (87.4%) delivered specimens. Seventy three males and 110 females received the containers. Sixty males (82%) and 100 (91%) females returned the samples. Three samples turned out to be positive (2%), all of them from females. For those who were sexually active (one or more partners for the last six months) the prevalence was 2.6% (117/160). IN CONCLUSION: The prevalence of asymptomatic Chlamydia infection in college students in this school was low, probably too low for screening to be cost effective. The procedure was not satisfactory because of the low percentage that enquired about their tests. It is therefore unsuitable in a screening program.

Solid phase synthesis and some hormonal activities of 1-deamino-4-L-valine-8-D-homolysine-and 1-deamino-4-L-valine-8-D-homoarginine-vasopressin.

1-Deamino-4-L-valine-8-DL-homolysine-vasopressin and protected 1-deamino-4-l-valine-8-D-lysine-vasopressin were synthesized by the solid phase method and were then converted into the title compounds (dVDHLVP and dVDHAVP) by tryptic digestion and epsilon-guanidination, respectively. The new hormone analogues exhibit only moderate antidiuretic potency, dVDHLVP 21 units/mg and dVDHAVP 31 units/mg, but since they are essentially devoid of pressor activity (o.o1 units/mg/ the A/P ratios are very high. In fact, dVDHLVP is the most specific antidiuretic agent in the lysine series known so far.

Syhthesis of peptides by fragment condensation on a solid support. I. Application in preparation of bradykinin.

Two tripeptides and one dipeptide, protected except at the carboxyl ends, have been prepared in solution and used as intermediates in a new synthesis of bradykinin on a solid support. Condensation of the two tripeptides to the resin was effected in satisfactroy yield with dicyclohexylcarbodiimide plus N-hydroxysuccinimide. The partial epimerization that might occur by such an approach was explicitly verified to be without practical importance in this case. The crude product contained only traces of impurities and yielded, after purification, bradykinin of high purity. Both the crude and purified bradykinin exhibited full biological activity.