Immunolabelling patterns of gap junction connexins in the developing and mature rat heart

The distribution of gap junctions in prenatal, postnatal, and adult rat hearts was studied by laser scanning confocal microscopy, using antiserum raised to a peptide (HJ) matching part of the sequence of connexin43 (a cardiac gap junction protein). Using digital reconstruction of optically-sectioned tissue volumes, a highly sensitive detection of immunolabelled gap junctions was achieved. The distribution of positive anti-HJ immunolabelling was regionalised in the prenatal heart from its first detection at 10 days post-coitus. High levels of immunopositive staining occurred in the trabeculae of the embryonic ventricles. Other zones of the early myocardium including early central conduction tissues had no detectable signal. The prenatal outflow tract, interventricular septum and a narrow zone of myocardium subjacent to the epicardial free wall also had low levels of immunopositive signal. During postnatal growth and in the adult rat heart, a marked distinction emerged between the central conducting tissues of the atria and ventricles. Whilst small immunostained gap junctions became detectable within the atrioventricular node on the atrial side of the junction, between the interatrial and interventricular septa, no immunolabelling was found within the ventricular branching bundle. This difference between the atrioventricular node and branching bundle is consistent with potential functional distinctions between these two structures, and is not consistent with the recent proposal that the His bundle and its branches act as an extended atrioventricular node in smaller mammals such as the rat. Ventricular Purkinje fibres, distal to the branching bundle, showed high levels of anti-HJ immunostaining. Organisation of gap junctions into intercalated disks within the ventricle proceeded late into intercalated disks within the ventricle proceeded late into the adolescent stages of heart growth. The distribution of a second connexin protein, MP70, not previously characterised in the heart, was studied using monoclonal antibodies. MP70 was transiently immunolabelled in the heart during the postnatal period, but only within valves. Previously, this protein has been reported only in the eye lens. MP70-containing gap junctions may represent a specialisation in avascular tissues, since blood vessels are not present in either the eye lens or the cusps of heart valves.

Effect of dietary fat on the distribution of mucosal mass and cell proliferation along the small intestine

This study investigated how substitution of long chain triglycerides for glucose in a mixed diet affects the overall small intestinal mucosal mass and the distribution of mucosal mass and cell proliferation along the small intestine. Four groups of eight female Wistar rats (180-200 g) were isocalorically fed mixed diets containing the essential fatty acid rich oil Efamol substituted for glucose at concentrations of 1.2%, 10%, 25%, and 50% total calories for 20 to 23 days. The small intestine was divided into three equal length segments and whole gut weights, mucosal weights, protein and DNA determined. Cell proliferation was estimated from the two hour accumulation of vincristine arrested metaphases in microdissected crypts at points 0%, 17%, 33%, 50%, 66%, and 100% small intestinal length. There were no differences between groups in parameters of overall small intestinal or distal segment mucosal mass. With increasing levels of fat, however, there was a significant trend for the mucosal mass of the proximal segment to fall and that of the middle segment to rise. The pattern of two hour metaphase accumulation reflected these changes. These regional changes in mucosal mass and cell proliferation may reflect differences in the sites of absorption of fat and glucose.

Effects of bolus doses of fat on small intestinal structure and on release of gastrin, cholecystokinin, peptide tyrosine-tyrosine, and enteroglucagon

To investigate the enterotrophic effects of bolus doses of long chain triglycerides, two groups of eight female Wistar rats were fed identical diets with 48.2% total calories as the essential fatty acid rich oil Efamol. To one group the oil was given in twice daily bolus doses by gavage, while for the other group the oil was mixed with the remainder of the feed and thus consumed over 24 hours. The animals were killed after 20 to 22 days. Bolus dosing significantly increased parameters of mucosal mass along the length of the small intestine in association with an increase in two hour accumulation of vincristine arrested metaphases in small intestinal crypts. In a second experiment, four replicate studies were carried out, each involving two groups of 12 rats respectively fed as described above. After 21 days one animal from each group was killed every two hours, providing regular plasma samples over 24 hours for measurement of gastrin, cholecystokinin, peptide tyrosine-tyrosine and enteroglucagon. Bolus dosing markedly enhanced release of peptide tyrosine-tyrosine and enteroglucagon, but not of gastrin or cholecystokinin. Thus, the enhanced enterotrophic effects of bolus doses of long chain triglycerides could be mediated by release of a distally located gut peptide, perhaps enteroglucagon.

Ventricular septal defects in a family of Yucatan miniature pigs

We have studied the hearts from a colony of Yucatan miniature pigs with spontaneously occurring congenital defects. Ventricular septal defect was encountered in 57 of 81 neonates from 15 consecutive litters. Of 73 hearts preserved for morphological assessment, 52 were found to have defects within the ventricular septum remarkably similar to those observed in humans with deficient ventricular septum. The defects, including 3 which had closed spontaneously, were perimembranous in 34, muscular in 12 and doubly committed and juxtaarterial in 6 hearts. Atrial septal defects were found in 12 of the 52 hearts with deficient ventricular septation; only 1 atrial septal defect was seen among 21 hearts with an intact ventricular septum. Anomalies of the aortic arch were associated with ventricular septal defect in 2 cases; 1 with a solitary arterial trunk and one with hypoplasia of the aorta and patent arterial duct. All these findings are replicated in human hearts. This strain of pig provides an ideal large animal model for morphologic and genetic investigations concerning the details of ventricular septation, including potential mechanisms of late spontaneous closure.

Effects of anesthetic agents and abdominal surgery on liver blood flow

The cause of postoperative liver dysfunction is often unclear, but a decrease in liver blood flow during anesthesia and/or major surgery may be important. Plasma half-life and clearance of indocyanine green were therefore measured in 42 patients before, during and after anesthesia and abdominal surgery. In 13 patients, liver blood flow was also estimated from indocyanine green extraction using hepatic vein catheterization. The major finding was an early decrease in estimated liver blood flow after induction of anesthesia, but not later during or after surgery. Mean indocyanine green half-life increased by 26% (p less than 0.005), mean indocyanine green plasma clearance decreased by 19% (p less than 0.01) and mean estimated hepatic blood flow decreased by 36% (p less than 0.005) during the first 30 min of anesthesia. These changes were greater in males and in patients older than 55 yr, but changes were similar with each of three anesthetic groups. Half-life, but not indocyanine green clearance, was also significantly prolonged by mid-operation in the older (greater than 55 yr) patients and in those undergoing lower abdominal surgery. We suggest that this period of reduced liver blood flow during anesthesia is caused by the effects of neuromuscular blocking agents and may contribute to postoperative liver damage.

Inhibition of red cell membrane lipid peroxidation by sulphasalazine and 5-aminosalicylic acid

The effects of sulphasalazine, 5-aminosalicylic acid (5-ASA), and sulphapyridine on peroxidation of red cell membrane lipids, measured as malondialdehyde production, were assessed. Sulphasalazine and 5-ASA, at concentrations of 10(-5)-10(-3) M significantly inhibit lipid peroxidation, suggesting an antioxidant action that may explain the efficacy of these drugs in treating inflammatory bowel disease. Sulphapyridine, which is not effective in inflammatory bowel disease inhibited malondialdehyde production at a concentration of 10(-3) M only.

Red cell lipid peroxidation and antioxidant enzymes in iron deficiency

Whether iron deficient RBC in humans have a reduced, or an increased, susceptibility to lipid peroxidation was studied in the iron deficiency states of primary proliferative polycythaemia and iron deficiency anaemia and related to changes in the activities of iron-dependent and non-iron dependent antioxidant enzymes. Susceptibility of RBCs to lipid peroxidation was increased when expressed per g Hb. However, this was a result of the low RBC Hb giving an increased membrane lipid: Hb ratio in the incubations. Results were normal when expressed either per cell, or per ml, RBC. Glutathione reductase was normal. Increased RBC superoxide dismutase activity in iron deficiency may be explained by the younger RBC population and reductions in glutathione peroxidase and catalase activities by the microcytic hypochromic changes and the lack of availability of iron, respectively. There is no evidence of an increased susceptibility of RBC to lipid peroxidation in iron deficiency.

Zinc improves the filterability of sickle erythrocytes at intermediate oxygen partial pressures

1. The deformability of erythrocytes from patients with sickle-cell anaemia was measured with a St George's blood filtrometer at a range of oxygen partial pressures and at four levels of zinc loading. 2. When incubated in buffered saline containing zinc and the chelator ethyl maltol, erythrocytes rapidly accumulated zinc and thus their oxygen affinity was increased. 3. Neither the oxygen partial pressure nor zinc loading affected the filtration of normal erythrocytes. 4. Deoxygenation of sickle erythrocytes greatly impaired filtration, although the initial filtration rate declined sharply at different oxygen partial pressures (between 70 and 35 mmHg) in different patients. 5. Low levels of zinc (0.03 +/- 0.003 mol of zinc/mol of haemoglobin tetramer) were without effect on sickle cells, but at zinc/haemoglobin ratios of 0.6:1 and above, the sharp fall in filtration rate occurred at oxygen partial pressures 8-25 mmHg below the oxygen partial pressure that impaired filtration of untreated cells. 6. Hence, the deformability of sickle erythrocytes in vitro can be improved by increasing the intracellular content of zinc to 20-fold above normal. Further studies are now required to examine the stability of zinc in erythrocytes, the effects of high intracellular zinc concentrations on erythrocyte viability, and the toxicity of zinc released from zinc-laden cells.

The influence of zinc status and malnutrition on immunological function in Crohn's disease

Cellular immunity is likely to be important in the pathogenesis of Crohn's disease; whether it is abnormal is not clear. The heterogeneity of patients with Crohn's disease probably underlies the disparity of reports, but attempts to determine which clinical features influence cellular immunity have been largely unsuccessful. This is probably caused by the omission of nutritional status as a potential factor, even though zinc deficiency has frequently been linked with abnormal immunity. Therefore, a detailed study of nutritional and tissue zinc status, nonspecific cellular immunity, and a measure of phagocytic function was performed in 32 patients with Crohn's disease and in a control group of 18 normal subjects and 12 patients with anorexia nervosa. Fourteen patients with Crohn's disease, all patients with anorexia nervosa, but none of the normal controls were malnourished. Peripheral blood lymphocyte population levels were normal in patients with Crohn's disease and in normal controls, but there was a small decrease in the levels of patients with anorexia nervosa. In vivo delayed hypersensitivity skin test responses were profoundly depressed in patients with anorexia nervosa and decreased in patients with Crohn's disease who were malnourished or receiving systemic glucocorticoids. In vitro lymphocyte transformation was reduced in malnourished patients with Crohn's disease, but there were only minor changes in patients with anorexia nervosa. There were alterations of in vitro immunoregulation in Crohn's disease, but they were not responsible for the abnormal lymphocyte transformation responses in malnourished patients. In vitro phagocytic function was reduced in patients with active Crohn's disease. These findings suggest that depressed in vivo and in vitro cellular immunity in malnourished patients with Crohn's disease is caused by a qualitative lymphocyte defect and that depressed in vivo but normal in vitro cellular immunity in anorexia nervosa is caused by a quantitative defect. Thus, malnutrition in Crohn's disease resembles kwashiorkor; in anorexia nervosa, it resembles marasmus. Tissue zinc status was mostly normal in Crohn's disease and anorexia nervosa, and zinc deficiency was not responsible for depressed nonspecific cellular immunity in either condition.

Cellular electrophysiology of neonatal and adult rabbit atrioventricular node

Adult and neonatal rabbit atrioventricular node (AVN) preparations were studied using transmembrane and surface electrogram recordings. Action potentials were categorized into four types, atrionodal (AN), nodal (N), "high" nodo-His (NH) (HNH), and "low" NH (LNH), according to their action potential characteristics and their location within the A-H interval. The electrophysiological parameters of the lower three regions were identical between the two age groups. Action potentials from the neonatal AN region were lower in amplitude and maximum diastolic potential than they were in the adult. The N cell action potential parameters did not differ between the two age groups, however, there did appear to be qualitative differences. AVN conduction times (A-H intervals) were the same in both age groups, as were the antegrade and retrograde refractory periods, and the Wenckebach intervals. Pacemaker activity was significantly greater in the neonates than in the adults and, in 11 of 13 neonatal preparations, originated in the AN region or higher. In 13 of 14 adult preparations, pacemaker activity resided within the AVN.

Transvenous cryoablation of the bundle of His

Cardiac dysrhythmias are a prominent cause of morbidity and mortality. Pharmacological treatment is ineffective in a large number of patients and is associated with many serious side effects. Thus, direct treatment of cardiac arrhythmias has been used with increasing frequency. Each form of direct treatment, such as surgical ablation, DC catheter ablation, radiofrequency catheter ablation, laser catheter ablation suffer serious drawbacks. Thus, we investigated the utility of transvenous catheter cryoablation of the bundle of His in five miniature swine, 40-60 lbs. in weight. Complete atrioventricular block was produced in each animal during cryothermia and persisted for 1 hour of observation in four out of five swine. In the fifth animal, 2:1 atrioventricular block within the atrioventricular node persisted for 1 hour of observation. Morphological and histologic examination revealed no dysfunction of capillaries and myofibriles in the atrioventricular node and proximal bundle of His. This potential mode of transcatheter therapy deserves further investigation.

Pyoderma gangrenosum after reduction mammoplasty

The authors report a case of pyoderma gangrenosum in a 37-year-old woman that occurred at surgical sites after reduction mammoplasty. The diagnosis was delayed, but treatment with intralesional triamcinolone resulted in complete resolution o the condition. Pyoderma gangrenosum in this setting can mimic infectious causes of wound necrosis. Early recognition of its characteristics features may prevent unnecessary and ineffective treatment, thereby avoiding frustration for both patient and physician.

Gastric ulcer healing: a comparison of enprostil versus ranitidine

Enprostil is a synthetic prostaglandin E2 analogue with gastric antisecretory and mucosal protective properties. We compared the effects of enprostil and ranitidine on the healing of gastric ulcers and the subsequent relapse rates over 6 months. Patients (N = 156) were recruited for a double-blind study from 12 centers in Europe; 71 were randomly assigned to oral treatment with 35 micrograms enprostil twice daily and 85 to 150 mg ranitidine twice daily for up to 8 weeks. Both groups were of similar demography; their healing rates were also similar. Cumulative intent-to-treat healing rates were at 4 weeks enprostil 48%, ranitidine 41%: at 6 weeks enprostil 65%, ranitidine 68%; and at 8 weeks enprostil 72%, ranitidine 80%. Of those patients who met all protocol criteria and completed treatment, and were endoscoped at the prescribed times, healing rates were at 4 weeks enprostil 55%, ranitidine 54%, at 6 weeks enprostil 75%, ranitidine 84%; and at 8 weeks enprostil 80%, ranitidine 90%. Relief of pain was rapid and similar in both groups. The incidence of adverse events was low and similar in the two groups. The treatment-free relapse rate at 6 months was enprostil 64%, ranitidine 49%; the median times to relapse were 169 and 203 days, respectively. Enprostil and ranitidine appear to be equally effective in healing gastric ulcers.

A double-blind trial of zinc supplementation in pregnancy

A double-blind randomised trial of oral zinc supplementation was carried out during the last two trimesters of pregnancy. Fifty-six women at risk of delivering a small-for-gestational-age baby received either zinc supplement (22.5 mg daily) or placebo. Twenty-nine of the women were compliant. Zinc significantly reduced the incidence of intrauterine growth retardation, and most measured indices of labour and fetal health were better in the supplemented group. Larger studies are now needed to confirm a role for selective zinc supplementation in at-risk pregnancies.

Detection of myosin gene expression in the developing heart using probes derived by polymerase chain reaction

The polymerase chain reaction provides a rapid method for the molecular cloning of DNA probes suitable for the detection of specific messenger RNA. We have used this approach to prepare probes specific for human cardiac myosin messenger RNA and demonstrate here the use of such probes in the analysis of human cardiac development by hybridization in situ to sections of fetal tissue. This combination of techniques is suitable for the detection of any messenger RNA for which sequence data are available, and offers a powerful new approach to the analysis of cardiac development.

Zinc depletion and complications of surgery

Zinc is essential for protein synthesis and reduced levels may impair recovery from surgery. To study this prospectively, clinical, anthropometric, haematological and biochemical indices of malnutrition were measured in 46 patients undergoing elective surgery and were related to the frequency and type of post-operative complications. In addition, leucocyte zinc levels, which are an estimate of tissue zinc levels, were measured. The diagnoses of the patients did not correlate with any of these parameters. Many patients were malnourished. 39% of the patients had a post-operative complication, of whom 8 had a wound complication. The frequency of complications as a whole was inversely related to serum albumin and transferrin levels, while wound complications were in addition associated with low leucocyte zinc levels. Malnutrition may therefore increase post-operative complications in general, but tissue zinc deficiency may contribute to wound problems.

The effects of dietary ligands on zinc uptake at the porcine intestinal brush-border membrane

Intestinal brush-border-membrane vesicles were prepared from the porcine small bowel by magnesium precipitation and differential centrifugation, and were functionally intact. The influence of dietary ligands on 65Zn uptake was determined using a 65Zn concentration of 5 microM, an incubation time of 1 min and a reaction temperature of 27 degrees, with a rapid filtration technique. At this low Zn concentration the addition of an excess of folate, histidine or glucose had no effect on Zn uptake. Addition of picolinate, citrate and phytate to the incubation medium significantly reduced Zn uptake at all concentrations of ligand examined. Any inhibitory effects of folic acid in vivo may thus be due to a mucosal rather than lumen interaction. Those ligands inhibiting absorption may have done so through the formation of Zn-ligand complexes, which are either insoluble, or which reduce the binding of Zn to its mucosal receptor. This in vitro model of Zn absorption is useful for comparing the effects of potential Zn-binding ligands in the diet.

Trial of low versus high osmolar contrast media in endoscopic retrograde cholangiopancreatography

A double-blind trial of low versus high osmolar contrast media in ERCP was performed. The results provide convincing evidence that the incidence of both biochemical and clinical pancreatitis is higher when the conventional high osmolar medium is used. It is therefore suggested that low ionic contrast media should be used routinely in ERCP.

Neutrophil zinc levels in psoriasis and seborrhoeic dermatitis

The median zinc content of neutrophils was significantly reduced in 16 patients with psoriasis in comparison to both normal controls and six patients with seborrhoeic dermatitis (P less than 0.05). This reduction was unrelated to the extent of skin involvement. Plasma and erythrocyte zinc levels were unchanged.

Heritable ventricular septal defect in Yucatan miniature swine

A heritable ventricular septal defect (VSD) was found in a strain of Yucatan miniature swine. The defect was determined to be a high membranous VSD analogous in anatomic location to the most common from of VSD in humans. Eighteen animals were studied clinically, hemodynamically and at necropsy to characterize the defect. Three mature animals developed pulmonary hypertension. Three animals were found to have a patent foramen ovale (PFO) in addition to the VSD. VSD is heritable probably due to polygenic factors. VSD in Yucatan miniature swine may be a suitable model of the human disease syndrome.