Cavo-portal transposition in rat: a new simple model

Background  

Liver transplantation in presence of diffuse portal vein thrombosis is possible by using caval blood as portal inflow, through cavo-portal transposition. However, clinical results are heterogeneous and experimental studies are needed, but similar hemodynamic conditions are difficult to obtain, especially in small animals. Herein we describe a new simple model of cavo-portal transposition in rat.     

Hemodynamic consequences of right ventricular isolation: the contribution of the right ventricular free wall to cardiac performance

Surgical isolation of the right ventricular free wall was performed in 10 dogs to evaluate both the hemodynamic effects of the procedure and the postoperative contribution of right ventricular free wall contraction to overall cardiac performance. Following the procedure, there was no significant differences in peak right ventricular systolic pressure, right atrial pressure, right ventricular stroke volume, or cardiac index. Cardiac index remained at preoperative levels over a wide range of filling pressures. However, there was a significant decrease in right ventricular stroke work (6.0 +/- 1.3 gm-m/m2 to 5.1 +/- 0.5 gm-m/m2; p less than 0.05). Pacing the isolated right ventricular free wall resulted in marked hemodynamic improvement compared with an electrically silent right ventricular free wall. Cardiac index increased from 1.7 +/- 0.2 L/min/m2 to 2.6 +/- 0.2 L/min/m2 (p less than 0.0005), and right ventricular stroke work went from 3.0 +/- 0.6 gm-m/m2 to 6.4 +/- 0.9 gm-m/m2 (p less than 0.0005). Right ventricular performance was also significantly related to the timing of right ventricular free wall contraction. Thus, the right ventricular free wall played an important role in the maintenance of normal cardiac hemodynamics.     

Human isolated small intestine: motor responses of the longitudinal muscle to field stimulation and exogenous neuropeptides

Summary (1) Longitudinal muscle strips from the human small intestine (jejunum/ileum) responded to electrical field stimulation (1–50 Hz) with frequency-related primary contractions which were largely atropine- (3 M) sensitive. When the tone was raised by addition of galanin (0.3 – 1 M), prostaglandin (PG) E₂ (1–10 M) or neurokinin A (NKA, 0.1 M), a frequency-related relaxation was evident which was potentiated by atropine. All the responses to field stimulation were abolished by tetrodotoxin (1 M), thus indicating their neural origin. (2) The atropine-sensitive primary contraction to field stimulation was virtually abolished by omega conotoxin fraction GVIA (CTX, 0.1–0.3 M) while the relaxations were CTX-resistant. The field stimulation-induced relaxations, which were observed in the presence of atropine and guanethidine (3 M), were also unaffected by apamin (0.1 M). (3) NKA and substance P (SP) produced a concentration- (1 nM–1 M for both peptides) related contraction, NKA being about 53 times more potent than SP. [Pro⁹]SP sulphone and [MePhe⁷]-NKB, selective agonists of the NK-1 and NK-3 receptor, respectively, were barely effective. On the other hand, [\Ala⁸]NKA(4–10), a selective NK-2 receptor agonist, had a potent contractile activity, similar to that of NKA. (4) Galanin (1 nM–1M) produced an atropine- and tetrodotoxin-resistant concentration-related contraction of longitudinal muscle of human isolated small intestine. The response to galanin did not show any sign of fading and was particularly suitable to study the evoked relaxations. (5) Calcitonin gene-related peptide (CGRP) (10–100 nM) consistently inhibited the nerve-mediated contractions of strips from the ileum while the effect on the jejunum was less pronounced. Vasoactive intestinal polypeptide (VIP, 0.1–1 M) inhibited nerve-mediated contractions both in the ileum and the jejunum. (6) These experiments indicate that both cholinergic excitatory and non-adrenergic non-cholinergic nerves affect motility of the longitudinal muscle of the human small intestine. Furthermore, several neuropeptides produce potent motor effects, the contractile response to tachykinins being apparently mediated by activation of NK-2 receptors.     

Serum concentrations of oestradiol-17beta, progesterone, relaxin and chorionic gonadotrophin during blastocyst implantation in natural pregnancy cycle and in embryo transfer cycle in the rhesus monkey

The present study was undertaken to assess the temporal association between the profiles of serum concentrations of oestradiol-17beta, progesterone, chorionic gonadotrophin (CG) and relaxin in pregnancies established naturally, and after embryo transfer, as well as in failed pregnancies in rhesus monkeys. In naturally mated cycles (group 1) a conception rate of 75% was obtained. In group 1, the mean day of CG detection in serum was 11.5 +/- 1.9 day post-ovulation, and for relaxin, 9.0 +/- 2.5 day post-ovulation. In group 2, embryo transfer to synchronous, non-mated surrogate recipients was performed; seven embryo transfer cycles yielded three pregnancies which were allowed to continue to term and normal infants were delivered. In embryo transfer cycles the mean day of CG detection was 14.8 +/- 1.8 day post- ovulation, and for relaxin, 11.4 +/- 2.6 day post-ovulation. A delay of about 3 days was observed in the appearance in circulation of CG (P < 0.05) and also of relaxin (P < 0.05) between natural mated and embryo transfer conception cycles. Significant differences (P < 0.05 for progesterone and P < 0.03 for oestradiol) were obtained for the areas under the curves for progesterone and oestradiol between days 12 and 16 in conception cycles compared with failed pregnancies. These data provide the first observation of the normal hormonal signals associated with maternal recognition of transferred embryos during the peri- implantation period, and suggest that the use of such an experimental primate embryo transfer model may help to elucidate components of maternal and embryonic signal-response mechanisms during embryo implantation.      

Decreased density of beta-adrenergic and muscarinic cholinergic receptor sites in the vasa nervorum of aged rats

The pharmacological profile and the anatomical localization of beta-adrenergic and muscarinic cholinergic receptors of the vasa nervorum were studied in sections of sciatic nerve using radioreceptor binding and light microscope autoradiography techniques. Sprague—Dawley rats of 4 and 24 months of age were used. [³H]Dihydroalprenolol (DHA) and [³H]quinuclidinyl benzilate (QNB) were used to label beta-adrenergic and muscarinic cholinergic receptors, respectively. The ligands were bound to sections of rat sciatic nerve in a manner consistent with the labelling of beta-adrenergic or muscarinic cholinergic receptors in the 2 age groups investigated. The dissociation constant (K_d) values (about 1.37 nM for [³H]DHA and 0.75 nM for [³H]QNB) did not significantly change between 4- and 24-month-old rats. The maximum concentration of binding sites (B_max) for [³H]DHA was decreased by about 35% in 24 in comparison with 4-month-old rats. The B_max value autoradiogaphy revealed the development of specific silver grains in the medial layer of epineurial and perineurial arteries in sections of sciatic nerve exposed either to [³H]DHA or [³H]QNB. The number of silver grains developed in epineurial and perineurial arteries of rats of 24 months is significantly lower than in animals of 4 months. The above results suggest the occurrence of an age-dependent loss in the density of beta-adrenergic and muscarinic cholinergic receptors of vasa nervorum.     

Ultrastructural quantitation of peroxidase- and elastase-containing granules in human neutrophils.

Previous ultrastructural studies of human neutrophils showed two distinctive granule types, the azurophil (peroxidase-positive) and the specific (peroxidase-negative). By identification of granules with peroxidase activity and those immunopositive for elastase antigen, the authors defined two subpopulations of azurophil granules, one that contained peroxidase activity and no measurable elastase antigen and another that contained elastase antigen associated with a small amount of peroxidase activity. They quantitated the peroxidase-positive as well as the elastase-positive granules in human peripheral blood neutrophils and found an average of 1536 +/- 69 peroxidase-positive granules per neutrophil. Of these, 399 +/- 20 were also elastase-positive. The average elastase concentration per neutrophil was 1.59 pg, and the average concentration per granule was 4 X 10(-3) pg. It is concluded that in normal individuals approximately one-third of the azurophil granules contain elastase antigen. Because neutrophil elastase has been implicated in the pathogenesis of emphysema, quantitation of its distribution within the cell presents an approach that may help define selective azurophil granule release and its relationship to the development of emphysema.