Modulating L-type calcium current affects discontinuous cardiac action potential conduction

We have used pairs of cardiac cells (i.e., one real guinea pig ventricular cell and a real-time simulation of a numerical model of a guinea pig ventricular cell) to evaluate the effects on action potential conduction of a variable coupling conductance in combination with agents that either increase or decrease the magnitude of the L-type calcium current. For the cell pairs studied, we applied a direct repetitive stimulation to the real cell, making it the "leader" cell of the cell pair. We have demonstrated that significant delays in action potential conduction for a cell pair can occur either with a decreased value of coupling conductance or with an asymmetry in size such that the follower cell is larger than the leader cell. In both conditions we have shown that isoproterenol, applied to the real cell at very low concentrations, can reversibly decrease the critical coupling conductance (below which action potential conduction fails) for a cell pair with fixed cell sizes, or, for a fixed value of coupling conductance, increase the maximum allowable asymmetry in cell size for successful conduction. For either of these effects, we were able to show that treatment of the real cell with BayK 8644, which more specifically increases the magnitude of the L-type calcium current, was able to mimic the actions of isoproterenol. Treatment of the leader cell of the cell pair (the real cell) with nifedipine, which selectively lowers the magnitude of the L-type calcium current, had effects opposite those of isoproterenol or BayK 8644. The actions of nifedipine, isoproterenol, and BayK 8644 are all limited to conditions in which the conduction delay is on the order of 5 ms or more, whether this delay is caused by limited coupling conductance or by asymmetry in size of the cells. This limitation is consistent with the time course of the L-type calcium current and suggests that the effects of calcium channel blockers or beta-adrenergic blocking drugs, in addition to being selective for regions of the heart that depend on the L-type calcium current for the upstroke of the action potential, would also be somewhat selective for regions of the heart that have discontinuous conduction, either normally or because of some pathological condition.     

Conversion of proximal to distal gastric bypass for failed gastric bypass for superobesity

The purpose of this study was to analyze outcome following malabsorptive distal gastric bypass (D-GBP) in superobese patients who were reoperated for recurrent obesity comorbidity after a failed standard gastric bypass (S-GBP). Twenty-seven formerly superobese patients with a failed S-GBP converted to a D-GBP were studied. The small bowel was anastomosed 250 cm from the ileocecal valve to the disconnected Roux limb; the bypassed small intestine was connected to the ileum 50 cm from the ileocecal valve in five patients between 1985 and 1986 and 150 cm from the ileocecal valve in 22 patients thereafter. Comorbidity was reassessed yearly following conversion to D-GBP. Malnutrition occurred in all five patients with a 50 cm "common tract"; all required further revision and two died of hepatic failure. Three of 22 patients with a 150 cm common tract were reoperated with bowel lengthening because of malnutrition. Initial body mass index was 57+/-2 kg/m2 and fell from 46+/-2 kg/m2 before revision to 37+/-2 kg/m2 at 1 year and 32+/-2 kg/m2 at 5 years after revision; the percentage of excess weight lost went from 30+/-4% to 61+/-4% at 1 year and 69+/-5% at 5 years after revision. Preoperative comorbidity in patients undergoing revision included 14 with insulin-dependent type II diabetes mellitus, 11 with sleep apnea, 14 with hypoventilation, 13 with hypertension, and two with venous stasis ulcers. Obesity comorbidity was corrected within 1 year in all but two patients with hypertension and remained stable in all patients followed for 5 years. Revision of a failed S-GBP to a 150 cm common tract D-GBP corrects failed weight loss and severe obesity comorbidity but requires nutritional support to prevent protein-calorie malnutrition, iron and fat-soluble vitamin deficiencies, and further revision in some patients to correct malnutrition. A 50 cm common tract has an unacceptable morbidity and mortality.     

The influence of riparian vegetation on water quality in a mixed land use river basin

Worldwide, agricultural activities are associated with environmental impacts including riparian degradation and increased waterway pollution. The Fitzroy Basin of Central Queensland lies within the Brigalow Belt Bioregion, which is currently experiencing the highest rates of tree clearing in Australia driven by grazing activities, and this is likely to increase riparian degradation. Local riparian condition, however, has not been consistently monitored within the Fitzroy Basin, and its relationship with water quality has not been well established. This study assessed riparian condition of waterways in the Fitzroy Basin using two established scoring methods (the Rapid Appraisal of Riparian Condition and the Australian Rivers Assessment System Habitat Assessment) and statistically investigated the relationship between stream water quality and local riparian condition. Twelve sites in six waterways were sampled four times over two years, during ambient (nonflood) conditions. Upstream creeks with poorer riparian condition had elevated dissolved organic carbon (DOC), dissolved manganese, sulfate, and total nitrogen (TN) concentrations. High concentrations of these water quality variables were associated with poor local riparian scores in principal components analysis. Dissolved manganese and sulfate were included in the multiple regression model for riparian scores (r values: 0.83 to 0.86; p < 0.001), and DOC and TN were very significantly negatively correlated with riparian scores (r values: ?0.55 to ?0.69; p < 0.001). Overall, the results suggest that protecting riparian vegetation in the Fitzroy Basin and restoring degraded riparian zones could aid in improving water quality in waterways within this region.     

Mindful revolution or mindless trend? Examining agile development as a management fashion

The growing adoption of agile methods of system development can be seen as broadly consistent with characteristics of a management fashion. However, the extent that fashions relate to how specific organizations actually adopt and use agile remains unclear. Based on five case studies, this research seeks to apply the concepts from management fashion theory to understand how organizations mindfully (or mindlessly) adopt agile methods. We find in some cases that agile appears to be characterized as a short-term, transitory trend, while in others it is embedded in an organization’s processes and culture. We identify three categories that distinguish between fashion patterns during agile adoptions: Crusaders, who exclusively adopt agile in a pure form; Tailors, who integrate agile and traditional approaches to fit their specific circumstances; and Dabblers who employ a few ceremonial agile activities alongside a traditional approach. The results from this study can encourage managerial awareness of the link between fashions and agile development, which can serve to highlight the unique opportunities to enhance mindfulness and avoid the pitfalls of mindlessness. By uncovering insights into the fashion-centric drivers of agile adoption, this research extends past theory related to both mindful innovation and management fashions.     

On the measurement of spontaneous platelet aggregation. The platelet aggregation test III. Methods and first clinical results

A new measuring device was developed for the study of "spontaneous" aggregating activity of thrombocytes. In the photometric platelet aggregation test (PAT III) 0.6 ml of platelet-rich plasma (PRP) are rotated in a disc-shaped cuvette at 20 rpm and 37 degrees C. Changes in optical density of PRP which are induced by the formation of platelet aggregates are continuously registered using a chart recorder. PAT III was developed for the detection of enhanced platelet aggregation, indicating a risk of thrombosis and thromboembolic complications. In 146 healthy individuals a certain percentage showed slight primary aggregation (alpha1) which in some cases was followed by marked aggregation (alpha2) at a certain time (Tr) after the beginning of rotation. The percentage of individuals showing alpha2 increased with age. An increase of plasma pH in the rotating sample, which was caused by diffusion of CO2, was an important conditioning factor for aggregation. The test results depended on the platelet count in PRP. Aggregation curves were suppressed by admixture of erythrocytes and lipid turbidity. The tendency of platelets to aggregate increased within 60-90 min following blood sampling. During this period the interval to the onset of aggregation (Tr) became shorter and the maximum aggregation speed (alpha 2) increased with time. PAT III yielded reproducible results when it was carried out more than 60 min after blood drawing. In a group of 327 diabetic patients "spontaneous" aggregation occurred more frequently in all age groups as compared with the controls. Additional equipment was available for the registration of ADP-, collagen-, or epinephrine-induced aggregation similar to Born's and O'Brien's method. The device can easily be mounted on an Eppendorf photometer without further alterations.     

Fibromuscular dysplasia and multiple dissecting aneurysms of intracranial arteries. A further cause of Moyamoya syndrome

A 16-year-old boy, who had sudden left-sided hemiplegia, died two weeks following onset of symptoms. A right carotid angiogram showed stenosis at the termination of the internal carotid artery. The middle cerebral artery had a beaded appearance and some of its branches were occluded. A basal "moyamoya" syndrome and transdural anastomoses were present. At autopsy, multiple intracranial dissecting aneurysms were found. Arteries of the body displayed fibromuscular dysplasia (FMD). The relevance of dysplastic changes of intracranial arteries and the relationship to moyamoya syndrome are discussed.     

Cancer in the "cold" breast thermogram

The hallmark of the normal breast thermogram is relative symmetry of vascular configuration and thermal content with preservation of the breast contour. Accepted criteria of abnormality are predicated upon graphic and thermal asymmetry with emphasis placed upon elevated temperature, an increase in the number of discernible vessels, and distorted vascular patterns. The association of a confirmed breast cancer and an avascular thermogram has been labeled a false negative. Avascularity ("cold" breast), particularly in the lower half, with normal vessels in the same location of the opposite breast is suggested as an additional characteristic of abnormality. Illustrative cases are presented.     

Seed transmission of cherry leaf roll virus in black cherry (Prunus serotina Ehrh.)

This is a survey about all factors influencing the osmotic pressure. The actual osmotic pressure in the plasma of healthy individuals is regulated essentially by the natrium ions and the corresponding anions. The one exception is the dysfunctioning diabetes mellitus with distinctly advanced hyperglycaemia. Syndromes with an accompanying azotemia demonstrate a seeming hyperosmolality as long as the osmotic pressure is measured or calculated by the customary method. The real and present osmotic condition can only be calculated when the blood urea concentration is no longer considered. It is proposed that the term "corrected osmolality" be used for the values determined in this manner.     

Danger of fire and explosion in anaesthetic and surgical departments

Corresponding to the fact that flammable anaesthetics are still very seldron in use the possibility of fires an explosions has diminished; the frequency of accidents caused by flammable colonic gases and by desinficients is about unchanged whilst a new kind can and dose occur: Fires and (occassional) explosions with "nonflammable" anaesthetic technics. A survey about 16 cases (including oxygen-fires) should be of interest for surgeons and intensive-care-people as well as for anaesthetists.     

Glucosuria of pregnancy: frequency of diabetes mellitus and renal glucosuria (author's transl)

From 1974 to 1979 352 pregnant women were referred to our diabetic outpatient clinic because of glycosuria during pregnancy. In 118 women (34%) oral glucose tolerance tests revealed a pathologic glucose tolerance. In 234 pregnant women (66%) a "renal glycosuria of pregnancy" was found to be the cause for the observed glycosuria. A pathologic glucose tolerance was relatively more frequent in the 3rd trimenon, whereas renal glycosuria was observed to be more frequent in the second trimenon.