Prazosin plasma concentration and blood pressure reduction.

Prazosin was administered to 16 patients with essential hypertension in an initial dose of 0.5 mg, after which the blood pressure (BP), pulse, and plasma concentrations of prazosin were measured at 0, 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, 8, and 24 hours. The dose of prazosin was then increased over 16 to 20 weeks, and similar sequences of measurements were obtained twice. Eleven patients completed the 20-week course. All patients did not respond in a similar way; two distinct patterns of BP and pulse response emerged, although there was no significant difference in the pharmacokinetic parameters, namely, absorption rate constant (Ka), maximum plasma concentration (Cpmax), time to reach the maximum concentration (Tmax), prazosin plasma half-life (T 1/2), elimination rate constant (kel), prazosin plasma concentration-time curve (AUC), and clearance. Patients in Group 1 had a marked reduction (52/30 mm Hg) of BP after the first dose of prazosin, no pulse increase, and needed a small dose of prazosin to maintain an adequate BP response. Patients in Group 3 had a minimal reduction in BP (14/13 mm Hg) after a first dose, a significant pulse increase, and needed a high dose of prazosin to control their BP. We conclude that this effect might be due to a different drug-receptor interaction, and the BP response and dose could be predicted from the response of the first dose of prazosin.

A study on IgE antibody-producing cells from the peripheral blood lymphocytes of atopic patients.

In the present study, the peripheral blood lymphocytes (PBL) of six rye-grass and 22 ragweed atopic patients demonstrated secretion of IgE antibody from 7-day cultures as measured by a sensitive ultra-low RAST. The RAST binding ranged from 1.5% to 21% whereas the cell supernatants from the PBL of eight non-atopic individuals showed little or no response (1.2%). The addition of antigens (rye grass 1 or AgE) or interleukin (IL-2) to the cultures on day 0 failed to cause an increase in response. But examination of PBL from four of these patients by a reverse hemolytic plaque assay showed that challenge of these cells by antigen or IL-2 caused an increase in the number of antigen-specific IgE plaque forming cells. The bulk of the IgE antibody secreting cells were located in a sheep red blood cell rosetted fraction (cell fraction 2) whereas most of IgE antibody PFC were found in the non-rosetting fraction (cell fraction 1). It appears that the reverse hemolytic plaque assay detects IgE antibody-producing cells which can still undergo immune regulation and may represent an earlier stage of B cell differentiation whereas the ultra-low RAST appears to measure spontaneous plasmablast cell IgE antibody response.

Vacuum-ultraviolet laser-excited spectra of Xe(2).

Fluorescence excitation of Xe(2) at 149.0 nm has been observed using a pulsed supersonic jet for dimer formation and cooling and using tunable coherent VUV radiation from four-wave mixing in Mg vapor for excitation. The resolved vibronic structure resulting from isotopic Xe(2) molecules has yielded unambiguous vibrational numbering (upsilon'=37-46), giving the following constants for the first O(+)(u) excited state of Xe(2): T(e) = 63 796(6) cm (-1), omega'(e) = 124.86(30) cm(-1), omega(e)X'(e) = 0.937(3) cm(-1), and D(e) = 4446(7) cm(-1).

Resonantly enhanced second-harmonic generation in zinc vapor.

Coherent second-harmonic radiation has been generated in atomic zinc vapor at 1792.5 and 1601 A from the 5(1)S(0)and 4(1)D(2) states, respectively, by two-photon resonance enhancement. Measurements of the ratio of second-to third-harmonic generation suggest the occurrence of static electric fields of ~5 kV/cm. These fields are caused by ionization of ~2% of the atoms in the focal volume of the incident laser beam.

Generation of continuously tunable coherent vacuum-ultraviolet radiation (140 to 106 nm) in zinc vapor.

It is shown that resonantly enhanced, four-wave frequency mixing in Zn vapor provides coherent vacuum-ultraviolet radiation that is continuously tunable over the range 140.4 to 106.3 nm (or ~23000 cm(-1)).

Intensity ratios of (2)D(5/2,3/2)?(2)S doublets in the two-photon absorption spectrum of Rb and Cs.

Absorption ratios of doublets arising from n(2)D(5/2,3/2)? n'(2)S transitions in Rb (n = 5-9, n' = 5) and Cs (n = 7-13, n' = 6) were measured by Doppler-free two-photon spectroscopy using a thermionic ion detector. The observed ratios agree with calculated values for transitions to the higher levels but differ significantly for levels n = 5 in Rb and n =7, 8 in Cs. These experiments also provide new lower bounds for the ionization potentials of Rb(2) (3.62 eV) and Cs(2) (3.682 eV).

Genotypic and phenotypic analysis of Mycoplasma fermentans strains isolated from different host tissues.

A correlation was found between the expression of a specific Mycoplasma fermentans surface antigen (Pra, proteinase-resistant antigen) and the site of isolation of the organism from the infected host. Strains which expressed Pra were most frequently associated with cells of bone marrow origin, and strains which lacked expression of Pra were most commonly isolated from the respiratory tract, genital tract, and arthritic joints, i.e., epithelial cell surfaces. Pra was previously shown to be resistant to degradation by proteinases and was hypothesized to play a protective role at the organism surface and perhaps to influence which host tissue site was colonized by the organism. The methods used for this phenotyping scheme required isolation and growth of the mycoplasma in quantities sufficient for immunoblot analysis using monoclonal antibodies. We wanted to determine a more rapid and less cumbersome technique to supplement this method for determining the Pra phenotype directly in clinical specimens. Here we describe PCR studies to investigate the movement of a previously identified M. fermentans insertion sequence (IS)-like element. These data showed a correlation between a specific IS genotype and the Pra+ phenotype. Production of a 160-bp product using a single set of IS-based primers was associated with expression of Pra. The genomic IS location resulting in the 160-bp product was determined by using Southern blot analysis and was found to be a stable insertion site characteristic of genotype I strains. Additional analyses of sequences within and flanking the IS insertion sites revealed another pair of PCR primer sites which resulted in the consistent production of a 450-bp amplicon. The stability of this site was dependent on the absence of the IS-like element between the primer sites. The production of this 450-bp amplicon correlated with the Pra mutant phenotype and was characteristic of genotype II strains. The data showed that the sequence within the IS may be unstable and that reliable genotyping sequences are more easily found in the stable genomic sites which flank the IS element.