Endurance training in dogs increases vascular responsiveness to an alpha 1-agonist

The effects of endurance training on vascular responsiveness to an alpha 1-agonist and the associated changes in baroreflex modulation of heart rate and vascular resistance were studied. Graded dosages of phenylephrine were given to eight treadmill-trained dogs and to eight untrained dogs; both groups were chronically instrumented and were sedated and resting when tested. These dosages were repeated after ganglionic blockade. Aortic pressure, cardiac output, central venous pressure, peripheral resistance, and heart rate were each averaged over 30 s before injection and 90 s after injection. The slope of the peripheral resistance-dose relationship was significantly increased in trained compared with untrained dogs in both the unblocked and blocked cases [unblocked: trained 0.89, untrained 0.47; blocked: trained 4.30, untrained 2.05 (mmHg.l-1.min)/(microgram.kg-1)]. The unblocked resistance slopes were reduced with respect to the blocked slopes by 77 (untrained) and 79% (trained). The slope of the heart rate-aortic pressure response was reduced, but not significantly, by endurance training. We conclude that 6 wk of endurance training in dogs resulted in a doubling of the vascular responsiveness to an alpha 1-agonist, with no significant change in the baroreflex regulation of resistance or heart rate.     

Strength conditioning in older men: skeletal muscle hypertrophy and improved function

The effects of strength conditioning on skeletal muscle function and mass were determined in older men. Twelve healthy untrained volunteers (age range 60-72 yr) participated in a 12-wk strength training program (8 repetitions/set; 3 sets/day; 3 days/wk) at 80% of the one repetition maximum (1 RM) for extensors and flexors of both knee joints. They were evaluated before the program and after 6 and 12 wk of training. Weekly measurements of 1 RM showed a progressive increase in strength in extensors and flexors. By 12 wk extensor and flexor strength had increased 107.4 (P less than 0.0001) and 226.7% (P less than 0.0001), respectively. Isokinetic peak torque of extensors and flexors measured on a Cybex II dynamometer increased 10.0 and 18.5% (P less than 0.05) at 60 degrees/s and 16.7 and 14.7% (P less than 0.05) at 240 degrees/s. The torque-velocity relationship showed an upward displacement of the curve at the end of training, mainly in the slow-velocity high-torque region. Midthigh composition from computerized tomographic scans showed an increase (P less than 0.01) in total thigh area (4.8%), total muscle area (11.4%), and quadriceps area (9.3%). Biopsies of the vastus lateralis muscle revealed similar increases (P less than 0.001) in type I fiber area (33.5%) and type II fiber area (27.6%). Daily excretion of urinary 3-methyl-L-histidine increased with training (P less than 0.05) by an average 40.8%. Strength gains in older men were associated with significant muscle hypertrophy and an increase in myofibrillar protein turnover.     

Production of pineapple plants in vitro

In vitro culture of pineapple (Ananas comosus) was studied to determine the efficiency of axillary bud culture for rapid propagation of several cultivars. The technique used maximizes the success rate of various steps in the production of pineapple plants. Rapid mass multiplication of plantlets started 9 months after explanting with a significant log phase. The number of plantlets obtained from the culture of a single bud by the thirteenth month ranged from 210 to 380 for Perolera; 300 to 350 for PR-1-67; and 40 to 85 for Smooth Cayenne. The method permits culture of a range of pineapple cultivars. Little morphological variation was observed in young regenerated plants.     

Non-replicating oral whole cell vaccine protective against enterotoxigenic Escherichia coli (ETEC) diarrhea: stimulation of anti-CFA (CFA/I) and anti-enterotoxin (anti-LT) intestinal IgA and protection against challenge with ETEC belonging to heterologous serotypes

An oral killed (non-replicating) whole-cell anti-ETEC vaccine was prepared by treating enterotoxigenic Escherichia coli strain H-10407 (ST + LT +; 078: H11: CFA/I) with a 100%-lethal amount of colicin E2. Colicin E2 is a potent DNA endonuclease which enters the target bacterial cells without disrupting cellular integrity. Thus the vaccine consists of intact cells lacking chromosomal and plasmid DNA but possessing a normal complement of antigens, including CFA/I and enterotoxin(s), unaltered by chemical- or heat-treatment. Young healthy volunteers were administered two oral doses, one month apart, of approximately 3 x 10(10) vaccine cells. Of 22 vaccinees, 17 (77.3%) showed an intestinal anti-CFA/I IgA response and 19 (86.4%) showed an increase in intestinal anti-LT IgA. Twenty of 22 (90.9%) vaccinees had antibody responses to either CFA/I, LT, or both antigens, demonstrating that colicin E2-treated CFA-positive E. coli cells are an efficient vehicle in terms of delivery of antigens to the gut immune system. We previously demonstrated protection of vaccinees against challenge with the living homologous ETEC (strain H-10407). In this study, two groups of 8 vaccinees were challenged with a diarrheagenic dose of virulent ST + LT + ETEC of heterologous serotype; one group was challenged with a CFA/I-positive 063: H- strain and the other group was challenged with a CFA/II-positive 06: H16 strain. Approximately 75% efficacy was achieved in both challenge groups. None of the 16 vaccinees who had responded to both CFA/I and LT became ill upon challenge while both of the vaccinees who had not responded to either antigen did.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunohistochemical localisation of natriuretic peptides in the heart and brain of the gulf toadfish Opsanus beta

Summary The distribution of natriuretic peptide immunoreactivity was determined in the heart and brain of the gulf toadfish Opsanus beta using the avidin-biotin peroxidase technique. Four antisera were used: the first raised against porcine brain natriuretic peptide which cross-reacts with atrial natriuretic and C-type natriuretic peptides (termed natriuretic peptide-like immunoreactivity); the second raised against porcine brain natriuretic peptide which cross-reacts with C-type natriuretic peptide but not with atrial natriuretic peptide (termed porcine brain natriuretic peptide-like immunoreactivity); the third raised against rat atrial natriuretic peptide; and the fourth raised against eel atrial natriuretic peptide. Natriuretic peptide- and porcine brain natriuretic peptide-like immunoreactivity was observed in all cardiac muscle cells of the atrium. In the ventricle, natriuretic peptide-like immunoreactivity was found in all cardiac muscle cells, however porcine brain natriuretic peptidelike immunoreactivity was confined to muscle cells adjacent to the epicardium. There was no discernible difference in the distribution of natriuretic peptide-like immunoreactivity and porcine brain natriuretic peptide-like immunoreactivity in the brain. Immunoreactive perikarya were observed only in the preoptic region of the diencephalon, and many immunoreactive fibres were found in the telencephalon, preoptic area, and rostral hypothalamus, lateral to the thalamic region. There was no immunoreactivity in any region of the hypophysis. A pair of distinct immunoreactive fibre tracts ran caudally from the preoptic area to the thalamic region, from which fibres extended to the posterior commissure, area praetectalis, dorsolateral regions of the midbrain tegmentum, and tectum. Many immunoreactive fibres were present in the rostral regions of the inferior lobes of the hypothalamus and in the dorsolateral and ventrolateral aspects of the rhombencephalon. No immunoreactivity was observed in the heart and brain using rat atrial natriuretic and eel natriuretic peptide antisera. Although the chemical structure of natriuretic peptides in the heart and brain of toadfish is unknown, these observations show that a component of the natriuretic peptide complement is similar to porcine brain natriuretic and/or porcine C-type natriuretic peptides. The presence of natriuretic peptides in the brain suggests that they could be important neuromodulators and/or neurotransmitters.     

Isolation and mapping of polymorphic cosmid clones used for sublocalization of the multiple endocrine neoplasia type 1 (MEN1) locus

Summary Multiple endocrine neoplasia type 1 (MEN1) is characterized by neoplasia of the parathyroids, the pancreas, and the pituitary. Tumorigenesis involves unmasking of a recessive mutation at the MEN1 locus, which has been mapped to the centromeric part of chromosomal region 11q. In order to localize the MEN1 gene further and to make its isolation possible, a number of new markers were isolated. Two radiation-reduced somatic cell hybrids were identified that only contained markers close to and flanking the MEN1 region. DNA from these hybrids was used for the construction of a cosmid library, and clones containing human inserts were isolated. In addition, cosmid clones were isolated for locus expansion of 7 other markers that were mapped to the 11q12–13.2 region. The 33 newly isolated clones together with 25 previously published markers from this region were analyzed in a panel of radiation-reduced somatic cell hybrids. From the hybridization pattern, the region was divided into 11 parts. New restriction fragment length polymorphisms were identified in 7 of the newly isolated cosmid clones and in one plasmid. These were then used to sublocalize meiotic cross-overs more precisely in two MEN1 families, thus refining the mapping of the disease gene.     

The polymorphism ApoB/4311 in patients with myocardial infarction and controls: the ECTIM study

Summary The polymorphism affecting codon 4311 of the apolipoprotein B gene (ApoB/4311) was investigated in a large case-control study in two French and one Northern Irish geographically defined populations. Cases were recruited 3 to 9 months after a myocardial infarction (MI) and controls were randomly selected from the population. The polymorphism was assessed using allele-specific oligonucleotides (ASO). The genotype frequencies of the ApoB/4311 polymorphism did not differ in Northern Ireland and France and were in Hardy-Weinberg equilibrium in all groups; strong associations with three other polymorphisms of the ApoB gene (XbaI, EcoRI, VNTR(34 repeats)) were observed and it was possible to identify highly sensitive and specific markers of the ApoB/4311 rare variant. Homozygotes for the ApoB 4311 rare variant were slightly less frequent in cases than in controls: 22 (4.4%) and 35 (6.7%) respectively (population adjusted ²=3.3 P<0.07), especially in Belfast: 6 (3.1%) and 12 (7.6%), respectively (P<0.06). Several lipid and lipoprotein parameters were measured. Consistently among control groups, rare homozygotes had lower mean levels of ApoB (P<0.02), triglycerides (P<0.02), and lipoprotein particles containing ApoE and ApoB (LpE:B; P<0.001) and a higher mean level of lipoprotein particles containing ApoAI and not ApoAII (LpAI; P<0.02) than heterozygotes and frequent homozygotes combined. The strong association between the ApoB/4311 polymorphism and LpE:B was also observed in patients with MI. When present in the homozygous form, the ApoB/ 4311 AsnSer variant is associated with a lipoprotein profile that is apparently favourable.