Additive interactions of calcitonin gene-related peptide and calcitonin on pancreatic exocrine function in conscious dogs

By convention, establishing a physiologic role for a gut peptide requires demonstration of biologic activity that can be reproduced by exogenous administration of the peptide in amounts that yield plasma concentrations that are not higher than those found after a meal. We have tested the hypothesis that the combined action of two inhibitory peptides may lower the effective doses of each. We further hypothesize that combined peptide responses may be responsible for the action of peptide hormones that have been difficult to demonstrate as physiologically relevant mediators, when examined as independently acting substances. In conscious dogs prepared with chronic pancreatic cannulas, stimulated pancreatic exocrine secretions were depressed in a dose-related manner by intravenous infusions of calcitonin (CT) and calcitonin gene-related peptide (CGRP). Doses of 2.0 nmol/kg/hr of both CT and CGRP yielded maximal inhibition of stimulated secretions of both bicarbonate (greater than 85% inhibition) and protein (greater than 55% inhibition). The lowest effective dose for either CT or CGRP, given alone, was 0.75 nmol/kg/hr, but when infused simultaneously, each at the subthreshold dose of 0.50 nmol/kg/hr, significant inhibition of protein and bicarbonate secretion was achieved. Combined infusions of the submaximal dose of 0.75 nmol/kg/hr resulted in an enhanced inhibitory response. To prove that this effect is not simply combined activation of a common receptor, we tested peptide YY (0.1 to 0.5 nmol/kg/hr) combined with CGRP and obtained similar results. Because a meal simultaneously releases a large number of active peptides, we speculate that such potentiated responses do occur physiologically. Cooperative interaction with other agents may be the primary mode of action for certain gut peptides.     

Varicose vein surgery using a pneumatic tourniquet: reduced blood loss and improved cosmesis.

A prospective controlled randomised study has been performed of 100 consecutive patients undergoing varicose vein surgery. One group underwent saphenofemoral flush ligation and multiple lower leg avulsions with the leg exsanguinated with a Rhys-Davies cuff, and ischaemia maintained with a pneumatic tourniquet. The other group underwent identical surgery but with a 30 degree head down tilt only. Blood loss was significantly less (13.5 +/- 12 ml vs 133 +/- 78 ml; P less than 0.01) and postoperative cosmesis was significantly improved in patients in the tourniquet group. Operating time was similar (27 +/- 11 min vs 30 +/- 13 min) in the two groups.     

Carbon Monoxide Mass Exposure in a Pediatric Population

Abstract. Objectives:To describe the outcomes of a mass carbon monoxide (CO) intoxication, and to calculate the CO half-life in a pediatric school-aged population.
Methods:A retrospective chart review was performed based on Regional Poison Center database information, hospital laboratory data, and medical records of the pediatric patients who sought care at one of 3 St. Louis area hospitals, after exposure to high levels of CO. Exposures occurred on January 5, 1996, after evidence of a CO leak was discovered at an area elementary school. Charts were reviewed for major demographics, symptoms reported, carboxyhemoglobin (COHb) levels and times, and level of effect.
Results:Information about 177 (35%) of the 504 children in attendance at school that day was available. Mean age was 8.7 ± 1.8 years (range 4–12 years). Symptoms were present in 155 (88%) of the 177 children for whom data were available. Initial COHb levels were obtained for 147 (83.1%) of the 177 children. First mean COHb level was 7.0% (95% CI = 6.6–7.5%). Second COHb level was obtained for 26 children with a mean of 2.7% (95% CI = 2.2–3.2%). Calculated half-life of COHb, on 100% 0₂ at 1 atm, was 44.0 minutes (95% CI = 39.6–48.2 minutes).
Conclusion:Some children had symptoms at COHb levels that traditionally have been considered nontoxic. The elimination of COHb was found to be more rapid in this population of children than reported in other studies.     

Blood flow acceleration in the carotid and brachial arteries of healthy volunteers: respective contributions of cardiac performance and local resistance

Summary— The influence of local resistance and cardiac performance on peripheral blood acceleration was investigated in 14 healthy male volunteers. Steady and pulsatile flow was studied in the brachial and in the common carotid arteries, ie, two territories that exhibit marked differences in resistive characteristics. Instantaneous blood velocity (V), mean blood velocity (V_m) and artery diameter (D) were evaluated at rest by an ultrasonic range-gated pulsed Doppler flowmeter using a double transducer probe, thus allowing the calculation of mean blood flow (Q). Mean local resistance (R) was obtained by dividing the mean arterial pressure by Q. The peak value of the local acceleration of the blood was obtained by computer-assisted calculation of the first derivative of instantaneous blood velocity (G_max = +dV/dt_max). Peak aortic blood acceleration (GAo) was simultaneously measured from the suprasternal notch using a pulsed Doppler velocity meter. In the brachial and the common carotid arteries, G_max was of a similar magnitude (551 ±30 and 555 ± 44 cm/s², respectively) despite major differences in the respective D, V_m, Q and R values. In neither artery was there a relationship between G_max and either resting Q or R. At the brachial artery level, G_max was positively related to GAo ( r = 0.79, P = 0.0008). At the common carotid artery level, there was a weak, although non significant relationship between G_max and GAo ( P = 0.08). Our results indicate that the local acceleration of peripheral blood flow in the brachial artery is related rather to upstream central impulse than to downstream hemodynamics, and suggest some regional differences in the hemodynamic determinants of the local acceleration of peripheral blood flow.     

Stricture and perforation of the esophagus: Overlooked threats in the Zollinger-Ellison syndrome

This study was undertaken to assess the frequency of significant esophageal involvement in the Zollinger-Ellison syndrome (ZES). In a consecutive series of 24 patients with this disease, 9 (37%) showed endoscopic evidence of acid-induced esophageal lesions ranging from erosive inflammation to ulceration with massive bleeding, severe stricture formation, and perforation. In 3 cases, pronounced esophagitis was known 1–5 years before the underlying disease was diagnosed. Severe esophageal complications developed despite treatment with antisecretory drugs. It is emphasized that the best way to limit such complications is by excision of the underlying gastrin-secreting tumor(s) when possible.

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Resumen El presente estudio fue emprendido con el propósito de determinar la frecuencia de afección ácido péptica significativa del esófago en pacientes con síndrome de Zollinger-Ellison. En una serie de 24 pacientes consecutivos con esta enfermedad, 9 (37%) exhibieron evidencia endoscópica de lesiones esofágicas inducidas por ácido, las cuales variaron entre inflamación erosiva y ulceración con sangrado masivo, estrechez severa, y perforación. En 3 pacientes se conocía la existencia de esofagitis severa entre 1 y 5 años antes del diagnóstico de la enfermedad de base. Se desarrollaron graves complicaciones esofágicas a pesar del tratamiento con drogas antisecretorias en 3 pacientes. Se hace enfasis en que la mejor manera de disminuir tales complicaciones es mediante la resección del tumor(es) secretor de gastrina, cuando ello sea posible.

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Résumé Nous avons entrepris cette étude pour établir la fréquence de participation oesophagienne dans le syndrome de Zollinger-Ellison. Pour une série de 24 patients présentant cette maladie, 9 (37%) avaient à l'endoscopie des lésions oesophagiennes dues à l'acidité allant de l'érosion inflammatoire à l'ulcération avec saignement important, sténose sévère, et perforation. Dans 3 cas, une oesophagite importante était connue 1–5 ans avant que la maladie sous-jacente soit diagnostiquée. Des complications oesophagiennes sévères se sont produites malgré le traitement antisécrétoire. Nous insistons sur le fait que le meilleur moyen de limiter ces complications est d'exciser chaque fois que possible la ou les tumeurs sous-jacentes sécrétant la gastrine.

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Presented at the International Association of Endocrine Surgeons in Toronto, Ontario, Canada, September, 1989.

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Supported by grants from the Swedish Medical Research Council, the Swedish Society of Medicine, the Anders Otto Swärd Foundation, and the Surgery Foundation of Skövde Central Hospital.     

The biology of breast tumor progression. Acquisition of hormone independence and resistance to cytotoxic drugs.

Many breast tumors appear to follow a predictable clinical pattern, being initially responsive to endocrine therapy and to cytotoxic chemotherapy but ultimately exhibiting a phenotype resistant to both modalities. Using the MCF-7 human breast cancer cell line as an example of an 'early' phenotype (estrogen and progesterone receptor positive, steroid responsive, low metastatic potential), we have isolated and characterized a series of hormone-independent but hormone-responsive variants (MIII and MCF7/LCC1). However, these variants remain responsive to both antiestrogens and cytotoxic drugs (methotrexate and colchicine). MIII and MCF7/LCC1 cells appear to mimic some of the critical aspects of the early progression to a more aggressive phenotype. An examination of the phenotype of these cells suggests that some hormone-independent breast cancer cells are derived from hormone-dependent parental cells. The development of a hormone-independent phenotype can arise independently of acquisition of a cytotoxic drug resistant phenotype.     

Congenital bacterial sepsis in very preterm infants.

The results of body fluid and surface cultures from 148 preterm infants less than 33 weeks gestational age obtained routinely on admission to a neonatal intensive care unit were reviewed. The aim was to determine the occurrence of congenital bacterial sepsis in this population and to examine whether surface cultures yielded information helpful in management. Gastric aspirate and umbilical, nasal and ear swabs were cultured and the results were compared to those of blood cultures. Nine infants (5.4%) had congenital bacterial sepsis diagnosed by positive blood cultures. Only the results of microscopy of gastric aspirate were available within hours of birth and before the results of blood culture. Microscopy of gastric aspirate, demonstrating pus cells, alone had a sensitivity of 0.86 in predicting congenital sepsis but a specificity of 0.49; the specificity, however, rose to 0.80 if both organisms and pus cells were observed on microscopy. Thus, only this combination was a useful pre-indicator of congenital sepsis. In infants who did not develop septicaemia, treatment was modified only if Streptococcus agalactiae was cultured from surface sites; in all such cases, the organism was grown from the ear swab. Our results demonstrate that congenital bacterial sepsis is common amongst very preterm infants admitted for neonatal intensive care but routine screening of surface cultures should be restricted to an ear swab only.     

Brain type creatine kinase in relation to oxygen desaturation in the blood of children with congenital heart disease

The concentration of brain type creatine kinase (CK-BB) was measured in blood from the internal jugular vein in 32 children (less than 1 year old) with congenital heart disease. In transposition of the great arteries the CK-BB levels were significantly higher than in children without cyanosis (10.1 +/- 4.1 vs. 3.0 +/- 0.5 ng/ml). A negative correlation was found for CK-BB concentration and arterial oxygen saturation (r = -0.41, p less than 0.02 for all children and r = -0.62, p less than 0.05 for those with tetralogy of Fallot). It is suggested that the increased CK-BB levels in the blood of cyanotic children reflect chronic cerebral hypoxia, which may explain other reports of reduced psycho-intellectual function in patients with cyanotic heart disease.     

Evaluation of metastatic cardiac calcification in a model of chronic primary hyperparathyroidism

Recent reports have fueled an interest in the prevalence and significance of metastatic calcium deposition in patients with chronic hyperparathyroidism. Experimental data are limited by the lack of suitable in vivo animal models. We have developed a model of marked hypercalcemia and overproduction of parathyroid hormone using somatic gene transfer. Briefly, the process involves infection of cultured rodent fibroblasts (RAT-1 cells) with a retroviral expression vector that contains the gene encoding human parathyroid hormone. Fibroblasts are grown to confluence on collagen-coated dextran microcarrier beads and are injected into the peritoneal cavities of syngeneic Fisher rats. Human parathyroid hormone production in rat serum is quantified by an immunoradiometric assay for human parathyroid hormone (1-84), which does not recognize rat parathyroid hormone. These rats consistently show production of human hormone within a week. Levels increase progressively, often to 1 ng/ml within 60 days of injection. Serum calcium showed a concomitant rise to an average of 15.5 mg/dl. In this study, 13 rats that had been transplanted with parathyroid hormone-producing fibroblasts were killed 80 days after injection. Examination of the skeleton revealed demineralization and histopathologic sequelae of parathyroid hormone excess with extensive osteoclastic bone resorption. Examination of the hearts revealed calcification in five of 13 hearts. There was no involvement of major coronary arteries or conducting systems, but there was calcification of cardiac myocytes, primarily in subepicardial region. This model may permit an understanding of the mechanisms for sudden cardiac death in severe hypercalcemia.