Differential response of hypertrophied rat hearts to various α1-adrenoceptor agonists

Summary— With respect to the heart, the prolonged existence of hypertension, both in man and in experimental animals is predominantly characterized by an increase in left ventricular myocardial mass. In this process, the autonomic nervous system plays an important role. Although endogenous catecholamine stimulation of the heart is mainly exerted via the β-adrenoceptors, in several mammalian species, the stimulation of cardiac α-adrenoceptors also mediates positive inotropic actions. We investigated the functional responses of isolated hypertrophied hearts taken from spontaneously hypertensive rats (SHR) and rats with an induced aortic stenosis (ASR) to various α₁-adrenoceptor agonists and compared them with those from age matched Wistar Kyoto (WKY) and "sham" operated controls. Accordingly, we studied the functional response to: methoxamine (α₁), cirazoline (α₁) and phenylephrine (α₁ > β₁). The inotropic response to the α₁-adrenoceptor agonists cirazoline and methoxamine proved to be significantly weaker in hypertrophied hearts from SHR and ASR than in non-hypertrophied hearts from WHY and "sham" operated controls ( p < 0.05). The inotropic response to phenylephrine remained intact in hypertrophied myocardial tissue. However, it was significantly reduced when the hearts were pre-treated with the intracellular Ca²⁺-antagonists ryanodine and TMB-8. These findings show that the mechanism of sarcolemmal Ca²⁺ release, activated by phenylephrine, is still intact in the hypertrophied myocardial cell. In conclusion, these data show that cardiac hypertrophy, be it of genetical or mechanical origin, leads to a reduced response of the isolated heart to α₁-adrenoceptor stimulation.     

Clinical Assessment of Gestational Age

There is disagreement among authors as to what criteria are most reliable in assessing postnatal fetal age. A comparison–for objectivity, accuracy, and frequency of use– of specific criteria was made using three independent examiners at different educational levels: a second-year medical student, a perinatal nurse practitioner, and a pediatrics resident. It was shown that trained examiners develop favorite criteria which differ among examiners and thus sacrifice accuracy; however, accurate assessment of fetal age can be accomplished by an examiner with minimum clinical knowledge.     

Development of an improved multi-pressure-sensor probe for recording muscle contraction in human intestine

We have developed an improved semiconductor recording probe for monitoring motility of the upper small intestine in humans. The probe consists of six ultraminiature silicon pressure sensors spaced 10 cm apart and encased in a flexible polyurethane sheath. The probe is small [2.67 mm (8F) diameter], is easily passed transnasally, and is tolerated by patients for prolonged recording periods (24–36 hr) with a minimum of discomfort. The initial semiconductor and catheter material were those designed for use in the cardiovascular system, but they proved to be easily damaged by gastric acid and enzymes. After improvement of this probe, we now have recordings from more than 100 patients for an approximate total of 6000 hr of recording time. The improved probe is a durable recording device that facilitates the investigation of motility of the small intestine in humans in health and disease.This study was supported by funds from the Medical Research Service of the Veterans Administration and by National Institutes of Health Clinical Research Center grant RR-82.     

III. Preoperative assessment of the airway: should anaesthetists be making use of modern imaging techniques?

Preoperative assessment of the central airway is concerned primarilywith the detection and evaluation of laryngotracheal stenosis.There are many causes of laryngotracheal stenosis; however,stenosis secondary to a thyroid goitre is one of the more commontypes requiring evaluation prior to general anaesthetic. A postero-anteriorchest and lateral thoracic inlet radiograph have been the primaryinvestigative tools used to assess the degree of tracheal compressionand deviation in both the transverse and antero-posterior planes.¹In many patients this type of imaging will suffice; however,computed tomography (CT) will more comprehensively detail theextent of tracheal stenosis and the degree of retrosternal extension.Compression of other structures by retrosternal     

Revision of Failed Gastric Bypass to Distal Roux-en-Y Gastric Bypass: A Review of 65 Cases

Background: No bariatric operation has been documented to effect adequate weight loss in all patients. Patients with inadequate weight loss or significant weight regain with an anatomically intact short-limb gastric bypass, of which the Fobi pouch operation (FPO) for obesity is a modification, are usually revised to a distal Roux-en-Y gastric bypass (DRYGBP) to enhance weight loss. Method: A retrospective review of the charts of all patients who had a revision to a DRYGBP at our Center during an 8-year period was carried out and the findings analyzed. Results: 65 patients who had the FPO had a revision to the DRYGBP.Most were super obese patients who, even though they had lost significant weight, were still morbidly obese. Some were patients who had not lost adequate weight or <40% excess weight, and a small number were patients who requested more weight loss even though they had a BMI of < 35. 15 patients developed protein malnutrition requiring supplemental feeding. 6 required rerevision to short-limb gastric bypass. Conclusion: Revision of short-limb gastric bypass to DRYGBP usually enhances weight loss but at a cost of an increased incidence of protein malnutrition.     

Intraventricular haemorrhage in the preterm infant without hyaline membrane disease

The clinicopathological associations of 33 singleton infants who died with intraventricular haemorrhage (IVH) without hyaline membrane disease (HMD) ('IVH only') were compared with those of 39 infants who died with IVH+HMD over the same gestation range in order to determine what factors other than those related to HMD may contribute to the pathogenesis of IVH. The incidence of 'IVH only' was inversely related to gestational age in the Hammersmith birth population, whereas the incidence of IVH+HMD rose to a peak at 28-29 weeks' gestation. Infants with 'IVH only' lived longer on average than those with IVH+HMD despite a lower birthweight and shorter gestation. Infants who died in the first 12 hours from 'IVH only' had suffered severe birth asphyxia but in those who died later the main symptom was recurrent apnoea. Fewer infants with asphyxia but in those who died later the main symptom was.recurrent apnoea. Fewer infants with 'IVH only' were given alkali therapy or were connected to the ventilator as compared to those with IVH+HMD, but there were no differences in alkali therapy in those who lived for 12 hours or more. In the 'IVH only' group there was a high incidence of haemorrhage from other sites and of bacterial infections. It is suggested that, in the absence of HMD, extreme immaturity is the main factor determining the occurrence of IVH. Birth asphyxia, apnoeic attacks, haemorrhage, and infections may play subsidiary roles, possibly through development of metabolic acidosis.     

Tissue and lineage-specific variation in inactive X chromosome expression of the murine Smcx gene

To understand how gene expression patterns are established on the inactive X chromosome during development, we have studied the murine gene Smcx, which is expressed from both the active and inactive mouse X chromosomes. In all tissues assayed, Smcx only partially escapes X inactivation, with expression levels from the inactive X allele approximately 30-65% that of the active X allele. Additionally, inactive X expression levels differed between extraembryonic and embryonic tissues and among different tissues from newborn and adult mice. Imprinted extraembryonic tissue had the lowest levels of inactive X Smcx expression, whereas the highest levels were in heart. These data suggest that the chromosomal basis of X inactivation differs among tissues, perhaps reflecting differences in the timing or regulation of inactivation in these cell lineages.      

Recurrent urinary tract infection in girls. Group with lower tract findings and a benign course

A group of girls is described with recurrent urinary tract infections characterized by predominantly lower tract symptoms. Clinical, laboratory, and radiography findings during the period of follow-up are presented. Infection persisted in most patients over several years. Response to medical and surgical treatment was unsatisfactory. The mean interval between the initial and most recent radiological study was 6 1/2 years. No case of renal parenchymal scarring was seen.