A Pneumatic Device for Rapid Loading of DNA Sequencing Gels

This work describes the design and construction of a device that facilitates the loading of DNA samples onto polyacrylamide gels for detection in the Perkin Elmer/Applied Biosystems (PE/ABI) 373 and 377 DNA sequencing instruments. The device is mounted onto the existing gel cassettes and makes the process of loading high-density gels less cumbersome while the associated time and errors are reduced. The principle of operation includes the simultaneous transfer of the entire batch of samples, in which a spring-loaded air cylinder generates positive pressure and flexible silica capillaries transfer the samples. A retractable capillary array carrier allows the delivery ends of the capillaries to be held up clear of the gel during loader attachment on the gel plates, while enabling their insertion in the gel wells once the device is securely mounted. Gel-loading devices capable of simultaneously transferring 72 samples onto the PE/ABI 373 and 377 are currently being used in our production sequencing groups while a 96-sample transfer prototype undergoes testing.     

Equal aspiration rates from postpylorus and intragastric-placed small-bore nasoenteric feeding tubes: a randomized, prospective study.

Postpylorus delivery of enteral feeding is perceived by many experts to be safer than intragastric delivery. To test this assumption, patients with similar Glasgow Coma Scores were given identical enteral formulas continuously via a 10-French nasoenteric tube, placed into the stomach or beyond the second portion of the duodenum. Observations were made for attainment of desired nutrition, bowel changes, and clinical signs of aspiration. Radiographs of the chest and abdomen were obtained every 3 days. If a tube migrated out of a chosen location, it was replaced. Thirty-three patients were studied. Seventeen patients were fed into the stomach and 16 patients were fed postpylorus. The mean duration of enteral feeding was 11.8 days for the gastric group and 10.9 days for the postpylorus group (p = NS). The time to deliver the desired kilocalories was 3.33 and 2.77 days (p = NS) for gastric and postpylorus-fed patients. Tubes displaced similarly in each group, gastric 0.647, postpylorus 0.750 per duration of feeding (p = NS). Chest radiographs met the criteria for aspiration pneumonia in 31.3% of gastric and 40% of postpylorus-fed patients (p = NS). Together, these data indicate that complications from enterally fed patients are equally common whether the distal port of the feeding tube is in the stomach or beyond the second portion of the duodenum.     

Prophylactic tranexamic acid decreases bleeding after cardiac operations

Thirty-eight patients undergoing a cardiac operation randomly received either tranexamic acid, a potent inhibitor of plasminogen, or placebo in an effort to determine whether prophylactic antifibrinolytic therapy reduces chest tube drainage. Twelve-hour blood loss was 750 +/- 314 (standard deviation) ml in the placebo group and 496 +/- 228 ml in the drug group (p = 0.0057). Fibrin split products were present more frequently in patients in the placebo group (17 of 20 compared with four of 18 in the drug group; p = 0.0002). Tranexamic acid markedly decreased plasminogen availability (112 +/- 104 units in the placebo group versus 36 +/- 18 units in the drug group, p = 0.0058). Plasma fibrinogen concentrations were similar in the placebo and drug groups. Patients in the placebo group received more fresh-frozen plasma and more mediastinal shed blood than those in the drug group. No coagulation-related complication occurred in the group receiving tranexamic acid. We conclude that prophylactic tranexamic acid can be administered safely to inhibit fibrinolysis during cardiac operations, decrease postoperative bleeding, and possibly decrease the frequency of blood product transfusion.     

Predicting cholangiocarcinoma in patients with primary sclerosing cholangitis before transplantation.

Patients with primary sclerosing cholangitis are at an increased risk of developing cholangiocarcinoma, which is difficult to diagnose because the biliary tree is already distorted. Eleven patients with primary sclerosing cholangitis who underwent orthotopic liver transplantation at this hospital were evaluated. Four patients had coincidental histologically proved cholangiocarcinoma. Patients with cholangiocarcinoma in contrast to patients without tumour presented with rapid onset of persistent jaundice, pruritus, and weight loss associated with an appreciable rise in bilirubin (8x v 2x) and alkaline phosphatase (3.5x v 1.2x) over one year. Cholangiography and computed tomography showed appreciably dilated intrahepatic bile ducts (3/4 v 0/7). The diagnosis of cholangiocarcinoma could only be established before operation in one patient by fine needle aspiration cytology. Tumour was recognised at operation in one other. Histological examination of hepatectomy specimens showed that patients with cholangiocarcinoma had less advanced histological features of primary sclerosing cholangitis. Multiple areas of carcinoembryonic antigen positive epithelial atypia and carcinoma in situ were found in all patients with cholangiocarcinoma. Cholangiocarcinoma recurred in two patients at 14 and 39 months after transplantation. Superimposed cholangiocarcinoma can be predicted in most patients with cholangitis before transplantation, although a definitive diagnosis is difficult to make. Their prognosis after successful transplantation is guarded.     

Environmental and genetic risk factors in early human atherogenesis: Lessons from the PDAY study

A multi-institutional study 'Pathobiological Determinants of Atherosclerosis in Youth' (PDAY) was initiated to document the natural history of atherosclerosis, its relationship to risk factors, and pathobiology of lesion development in young subjects. Pathology laboratories in nine centers collected arteries and tissues from over 2000 persons from 15 through 34 years of age whose deaths were attributed to homicides, accidents, or suicides. Arteries were evaluated for lesions, and risk factors were analyzed in a central laboratory. Postmortem risk factors included serum lipoproteins, serum thio-cyanate (smoking), glycohemoglobin (diabetes), thickness of panniculus adiposus (obesity), small renal artery changes (hypertension) and apoprotein isoforms. This study documents the development of atherosclerosis at an early age. It also shows that the recognized risk factors for coronary heart disease are associated with lesion development in the arteries of these young subjects. The PDAY study has a counterpart in Japan where the development of atherosclerosis has been studied in young subjects. This Japanese study, in a population in which coronary heart disease has not yet become a major epidemic, has findings quite similar to the findings from the PDAY study. Studies of atherosclerosis in both Japan and the USA provide strong justification for reducing risk factors in young persons.     

Methods for estimating numbers of motor units in biceps-brachialis muscles and losses of motor units with aging

This paper presents a new method, here applied to the biceps-brachialis muscles, for estimating motor unit numbers in healthy subjects. This method combines isometric contraction, intramuscular needle electrode recordings, and spike-triggered averaging techniques to measure the sizes of motor unit potentials as recorded in the innervation zone with surface electrodes. The number of motor units is then estimated by division of the maximum biceps-brachialis "M" potential recorded with the same surface electrodes and evoked by supramaximal stimulation of the musculocutaneous nerve, by the mean of at least 10 surface-recorded motor unit potentials. The requisite intramuscular recordings provide additional information as to innervation density, incidence of linked potentials, and impulse blocking, phenomena that are particularly common in neurogenic and myogenic disorders. There was clear evidence of losses of motor units in older subjects: subjects over 60 years of age having approximately half the numbers of motor units of subjects under 60 years of age.     

Cryopreservation of human mononuclear cells for quality control in clinical immunology. I. Correlations in recovery of K- and NK-cell functions,surface markers,and morphology

Cryopreserved human peripheral blood mononuclear cells (PBMC) were tested for natural killer (NK) and antibody-dependent cellular cytotoxicity (ADCC) and for high-affinity (29°C) and total (4°C) rosette formation with sheep erythrocytes. PBMC produced variable NK activity following freezing and thawing, but consistently reacted well in ADCC. A significant correlation was found between low NK activity and a decreased percentage of low-affinity rosette-forming cells. On the contrary, the number of large granular lymphocytes (LGL), among which NK cells are restricted, and the reactivity with the monoclonal antibody OKT10, which recognizes the majority of LGL in the peripheral blood, were not significantly altered by cryopreservation. Cryopreserved cells proved to be excellent controls for determining the day-to-day variability of the NK assay and for selecting optimum conditions for this test in the clinical immunology laboratory.