Angiotensins in plasma of hypertensive rats and human.

The plasma levels of des-aspartate-angiotensin I (DAA-I) in three models of hypertensive rats and hypertensive subjects were determined and compared with their normotensive controls. The rationale for the study was based on our earlier findings showing that DAA-I is a physiological angiotensin peptide that is involved in the pathophysiology of the cardiovascular system. The determination was carried out by the technique of capillary electrophoresis. Plasma level of angiotensin I, angiotensin II, and angiotensin III was also determined as a measurement of the status of the renin-angiotensin system in the different models of hypertension. DAA-I was found to be significantly lower in the spontaneously hypertensive rats (SHR) (46.6 +/- 2.5 pmol/l compared to 66.1 +/- 3.4 pmol/l for the normotensive control Wistar Kyoto rats), renal hypertensive rats (54.2 +/- 5.1 pmol/l compared to 72 +/- 2.5 pmol/l for the normotensive control Sprague-Dawley rats), and essential human hypertensive subjects (15.2 +/- 0.9 pmol/l compared to 19.5 +/- 2.5 pmol/l for the normotensive adult), whilst plasma concentration of angiotensin I and angiotensin II is reflective of the state of the renin-angiotensin system in the particular model of hypertension. When the SHR and human hypertensive subjects were treated with an angiotensin converting enzyme (ACE) inhibitor, the plasma level of DAA-I increased significantly. These findings suggest that the low plasma level of DAA-I could be a characteristic defect of the renin-angiotensin system in the two genetic models of hypertension (SHR and human essential hypertensive subjects). The increase of the nonapeptide following ACE inhibitor treatment could be an important hitherto unrecorded contributory factor to the effectiveness of ACE inhibitors in combating heart pathology.

H2-uptake activity, spectra, reduction potentials, and kinetics of iron release on the surface of iron core from Azotobacter vinelandii bacterial ferritin.

Bacterial ferritin from Azotobacter vinelandii (AvBFo) has a function in H2 uptake. The Fe3+ reduction on the surface of the iron core from AvBFo is accompanied simultaneously by H2 uptake, with a maximum activity of H2 uptake of 450 H2/AvBFo. A reduction potential of -402 mV for iron reduction on the surface of the core is found. A shift to the red the protein absorbance peaks ranging from 280 to 290 nm is observed between pH 5 and 9 under 100% H2 reduction. The reduction potential for iron release becomes negative at a rate of 0.025 mV/Fe2+ released. The kinetics of iron release on the surface of the core is a first-order reaction.

Comparison of high-resolution structures of the diphtheria toxin repressor in complex with cobalt and zinc at the cation-anion binding site.

The diphtheria toxin repressor (DtxR) from Corynebacterium diphtheriae is a divalent-metal activated repressor of chromosomal genes responsible for siderophore-mediated iron-uptake and of a gene on several corynebacteriophages that encodes diphtheria toxin. Even though DtxR is the best characterized iron-dependent repressor to date, numerous key properties of the protein still remain to be explained. One is the role of the cation-anion pair discovered in its first metal-binding site. A second is the reason why zinc exhibits its activating effect only at a concentration 100-fold higher than other divalent cations. In the presently reported 1.85 A resolution Co-DtxR structure at 100K, the sulfate anion in the cation-anion-binding site interacts with three side chains that are all conserved in the entire DtxR family, which points to a possible physiological role of the anion. A comparison of the 1.85 A Cobalt-DtxR structure at 100K and the 2.4 A Zinc-DtxR structure at room temperature revealed no significant differences. Hence, the difference in efficiency of Co2+ and Zn2+ to activate DtxR remains a mystery and might be hidden in the properties of the intriguing second metal-binding site. Our studies do, however, provide a high resolution view of the cationanion-binding site that has most likely evolved to interact not only with a cation but also with the anion in a very precise manner.

Cloning and characterization of PO22, a pollen-expressed gene in alfalfa.

Genomic and cDNA clones have been isolated for a new gene (PO22) expressed in mature pollen of alfalfa. PO22 represents a single- or low-copy gene containing 4 introns, 2 transcriptional start sites, and coding for a predicted protein of 340 amino acids with no signal peptide and a coiled coil structure of 39 amino acids near the carboxyl end. The amino acid sequence of PO22 is 38% identical to that of an early nodule-specific gene (ENOD8), also from alfalfa.

Effect of a membrane interactive peptide on plant cells of canola (Brassica napus) and two fungal pathogens.

A membrane interactive peptide was toxic to microspores, pollen and protoplasts of canola in the 1-5 µM concentration range. Similarly, at 5.0 µM the peptide completely inhibited germination of conidia ofVerticillium albo-atrum; however, when tested with conidia of a virulent isolate of blackleg (Leptosphaeria maculens), a fungal pathogen of canola, much higher levels (>30 µM) of the peptide were required to reduce or arrest germination and growth of the conidia. When testing the relative toxicities of novel peptides on plant cells and their pathogens, pollen germination is a simple, rapid and reliable alternative to protoplasts.

Chinese medical school exit objectives: a multi-institutional survey of teacher opinion.

This paper describes a collaborative survey of Chinese medical school teacher opinion concerning clinical behaviours and skills that Chinese students should be expected to demonstrate prior to graduation from medical school. Selected teachers from four Chinese medical schools indicated whether each of 77 objectives was: essential for every student to know or demonstrate prior to graduation; useful but not essential; or not applicable to their educational programmes. Results show teachers' expectations regarding some of the behaviours and skills Chinese medical school teachers consider to be important for students to learn. Forty-nine per cent of the exit objectives were regarded as essential by 75% or more of the teachers. The most essential objectives involved performing clinical procedures, collaborating and communicating with health care professionals, conducting organ system examinations, formulating hypotheses and defining problems. Other essential objectives were concerned with communicating with patients and their families, maintaining currency within the discipline, and recognition, evaluation and triage of patients with life-threatening or chronic conditions. Exit objectives related to health promotion and risk assessment were regarded as useful but not essential at the undergraduate level. Implications for Chinese medical education are discussed.

Analysis of RFLPs and DNA deletions in the Chinese Duchenne muscular dystrophy gene.

Sixty-nine unrelated Chinese DMD patients were studied with a series of genomic and cDNA probes. Analysis of 13 polymorphic sites showed that pERT87-1, 87-8, 87-15, and XJ probes gave favourable allele frequencies in the Chinese population, and nearly 90% of the DMD families in this study were informative for prenatal diagnosis and carrier detection using these four polymorphic markers. Nine out of 69 (13%) were also found to have gene deletions using a panel of genomic probes. However, when using cDNA probes, deletions were found in 56.5% of the patients. The deletions were concentrated in the areas of probes 7 and 8, giving a proportion of about 80% of all deleted patients in this study. All these results provide valuable information for planning prenatal diagnosis programmes for DMD in China.

[Clinical observations on LRH-A used for contraception by luteolysis in normal women--analysis of 88 cases].

PIP: 88 healthy female volunteers, ages 17-42, with regular menstrual cycles entered into the trail with a new superactive stimulatory analos of the LRH-A (D-A1a6-EA10) -LH for contraception by luteolysis. The LRH-A was administered intranasally or intramuscularly (im) on days 6-8 following the LH peak/BBT temperature rise for 1-5 successive cycles. Group 1 consisted of 12 women who were given 1000 mcg LRH-A intranasally for 4 days; group 2 consisted of 18 women who were given a single dose of 200 mcg LRH-A im; group 3 had 34 women who were given 200 mcg im b. i. d. for 1 day; and group 4 had 24 women who were given 200 mcg im g.d. for 3 days. During the treatment cycles, no additional contraceptive was used. Luteolysis was defined as the reduction in plasma progesterone and estradiol levels and the shortening of the luteal phase associated with an infertile cycle. Luteolysis occured in 9 of 12 cycles in group 1 with no shortening of the luteal phase in 3 cycles; in 13 of 18 cycles in group 2 with no shortening of the luteal phase in 5 cycles; in 32 of 34 cycles in group 3 with no decline of progesterone in i cycles; in 115 of 120 cycles in group 4 with 5 pregnancies occurring. The results showed that treatment with LRH-A seemed to be more efficient when applies in twice a day or q.d. for 3-4 successive days as compared with a single dose. No severe side effects were observed durin treatment and apparently normal cycles occurred immediately after withdrawal of treatment. The above data indicate that an adequate dose of LRH-A can provide a fairly good luteolysis result in women at the midluteal phase. However, more extensive study is necesary before a long-term application of LRH-A for contraception by luteolysis can be considered practical.^ieng

Etiologic studies of epidemic hemorrhagic fever (hemorrhagic fever with renal syndrome).

Two strains of epidemic hemorrhagic fever (EHF) virus were isolated from the lung tissues of Apodemus agrarius mice that were captured in an area where EHF is endemic. The strains were isolated by passages in A. agrarius mice from a nonendemic area. Identification of the isolates by usual procedures was confirmed by repeated blind tests with coded sera. Contamination with certain known viruses such as reovirus, adenovirus (types 3 and 7), and other pathogens, such as murine typhus rickettsiae and Leptospira, which may be naturally present in wild rodents, appeared to have been ruled out. The antigen slides made from these isolates are in use in the specific diagnosis and seroepidemiologic studies of EHF. The first successful application is the serodiagnosis of a mild type of hemorrhagic fever that occurs with characteristic epidemiologic features in certain provinces of China.

Large-scale purification of prothoracicotropic hormone of the silkworm (Bombyx mori).

Prothoracicotropic hormone has been successfully extracted from as many as 2,800,000 silkworm male adult heads and purified partially through an 8-step procedure. Approximately 7 microgram of the crude preparation ("crude PTTH") shows activity in the debrained Samia pupa test. A further 4-step chromatographic purification of the "crude PTTH" derived from 100,000 Bombyx heads yields 3.4 mg of purified preparation ("highly purified PTTH"), of which 7 ng causes adult development in a debrained Samia pupa.