Immunohistochemical video-microdensitometry of myocardial collagen type I and type III

Collagen is an essential part of the cardiac interstitium. Collagen subtypes, their location, total amount and the architecture of the fibrillar network are of functional importance. Architecture in terms of density of the fibrillar network is assumed to be reflected by the intensity of immunohistochemical staining of collagen. The aim of this study was to evaluate a video-based microdensitometric method for quantifying density expressed as absorbance of collagen subtypes I and III stained with an indirect immunoperoxidase method in myectomy specimens of patients with hypertrophic obstructive cardiomyopathy. Various factors influencing the immunohistochemical staining product and the technical properties of the image analysis system were investigated. Linearity between collagen concentration and the absorbance of the immunohistochemical staining product was demonstrated for collagen I using a dot-blot technique. Immunohistochemical collagen staining and density measurement were easily reproducible. The cardiac disability of the patients was assessed according to the New York Heart Association (NYHA) criteria. There was a significant increase in collagen type I density with higher NYHA class, whereas no significant association was found for total collagen area fraction. Thus, video-based microdensitometry gives further insight into the structural remodelling of myocardial collagens and reveals their significance in the process of heart failure in hypertrophic cardiomyopathy.     

Strain differences in adrenal microsomal steroid metabolism in guinea pigs

We recently reported that CYP2D16, a xenobiotic-metabolizing P450 isozyme, was expressed at higher levels in adrenal microsomes from inbred Strain 13 guinea pigs than in those from outbred English Short Hair (ESH) animals. Studies were done to determine if there also were strain differences in adrenal microsomal steroid metabolism. In both inner (zona reticularis) and outer (zona fasciculata plus zona glomerulosa) zone preparations of the adrenal cortex, 21-hydroxylase activities were greater in microsomes from ESH than from Strain 13 guinea pigs. By contrast, 17alpha-hydroxylase activities were similar in the two strains. In both strains, 21-hydroxylase activities were greater in inner than outer zone microsomes, but the opposite was found for 17alpha-hydroxylase activities (outer>inner). Northern and Western analyses revealed higher levels of CYP21 mRNA and protein in adrenals from ESH than Strain 13 guinea pigs, but there were no strain differences in CYP17 mRNA or protein concentrations. Despite the zonal differences in adrenal 17alpha-hydroxylase and 21-hydroxylase activities, CYP17 and CYP21 mRNA and protein levels were similar in the inner and outer zones within each strain of guinea pig. The results demonstrate strain differences in microsomal steroid metabolism that are explained by differences in CYP21 expression. By contrast, the zonal differences in steroid hydroxylase activities may be attributable to post-translational mechanisms.     

Direct endoscopic percutaneous jejunostomy (EPJ). Clinical results

Direct puncture of the small bowel under endoscopic guidance (direct EPJ) is possible in patients whose stomach has been removed or whose small bowel cannot be punctured by other methods. From January 1990 to June 1992 a total of 39 patients underwent successful direct EPJ at our institution. The indications were malnutrition after partial or total gastrectomy (n = 19), insufficient anastomosis or a stenosis after esophageal resection and esophagojejunostomy (n = 13), esophageal perforation (n = 3), fistulas (n = 2), or severe trauma (n = 2). The tubes were inserted at the bedside under local anesthesia using the string pull-through technique. The procedure was attempted in five other patients but it was technically impossible to insert the tubes in these patients. Postoperative enteral feeding was possible in all 39 patients whose direct EPJ was successful. Complications included tube dysfunction due to plugging and fracture in five patients, pressure-induced enteric ulcers in two, and local infections in three patients. The ulcers and infections were managed conservatively. We conclude that direct EPJ is a safe, effective alternative to surgical catheter-jejunostomy.     

B lymphocytes are critical antigen-presenting cells for the initiation of T cell-mediated autoimmune diabetes in nonobese diabetic mice

Nonobese diabetic (NOD) mice genetically deficient in B lymphocytes (NODJg mu(null)) are resistant to T cell-mediated autoimmune insulin-dependent diabetes mellitus (IDDM). Ig infusions from diabetic NOD donors did not abrogate IDDM resistance in NODJg mu(null) mice. However, T cell responses to the candidate pancreatic beta cell autoantigen glutamic acid decarboxylase (GAD), but not the control Ag keyhole limpet hemocyanin, were eliminated in NODJg mu(null) mice. To initially test whether they contribute to IDDM as APC, NOD B lymphocytes were transferred into NODJg mu(null) recipients. B lymphocytes transferred into unmanipulated NODJg mu(null) recipients were rejected by MHC class I-restricted T cells. Stable T and B lymphocyte repopulation was achieved in irradiated NODJg mu(null) mice reconstituted with syngeneic bone marrow admixed with NOD B lymphocytes. IDDM susceptibility was restored in NODJg mu(null) mice reconstituted with syngeneic marrow plus B lymphocytes, but not with syngeneic marrow only. T cell responses to GAD were restored only in NODJg mu(null) mice reconstituted with syngeneic marrow plus B lymphocytes. Hence, B lymphocytes appear to contribute to IDDM in NOD mice as APC with a preferential ability to present certain beta cell Ags such as GAD to autoreactive T cells.     

Factors affecting serum oxytetracycline levels in beef calves

Fifteen Aberdeen Angus steers, 295-364 kg, were dosed with either 4.4 or 11 mg of oxytetracycline hydrochloride/kg im. The antimicrobial activity of the serum was determined periodically, and the resulting data were treated statistically to determine the sources of variation. Variance in serum levels of oxytetracycline activity was attributed to dose, time of bleeding, order of dosing, animal, and assay. The total variance component was proportionately greater for the 11-mg/kg dose than for the 4.4-mg/kg dose. Animal variance increased with the higher dose level of oxytetracycline. The influence of dose on serum level was tested by applying a t test to the mean serum levels and their standard deviations at each bleeding time. The 4.4- and 11-mg/kg serum levels were significantly different (p less than 0.01) at all bleeding times. The 4.4-mg/kg serum levels mutliplied by 2.5 were not significantly different (p less than 0.05) from the 11-mg/kg serum levels at all bleeding times.     

Recurrent urothelial tumors following surgery for transitional cell carcinoma of the upper urinary tract

A retrospective analysis of 74 cases of transitional cell carcinoma of the renal pelvis and ureter treated at this institution over the past 30 years is presented. When nephrectomy alone or incomplete nephroureterectomy was performed, subsequent transitional cell carcinoma developed in 30% of the ureteral stumps. Subsequent bladder carcinoma occurred in 25% of the patients with primary upper urinary tract carcinoma. The type of initial surgery performed did not appear to influence this incidence of subsequent bladder tumors. Contralateral upper urinary tract carcinoma developed in only one patient. When nephroureterectomy is performed for carcinoma of the renal pelvis and ureter, a cuff of bladder that includes the ureteral orifice should be removed to obviate recurrent disease in the ureteral stump. Since single-incision nephroureterectomy did not include the intramural ureter in 50% of the cases in which it was performed, a second incision may be required for adequate exposure.     

A quantitative methodology for reactor vessel pressurized thermal shock decision making

The recent operating experience of the Pressurized Water Reactor (PWR) Industry has focused increasing attention on the issue of reactor vessel pressurized thermal shock (PTS). Previous reactor vessel integrity concerns have led to changes in vessel and plant system design and to operating procedures, and increased attention to the PTS issue is causing consideration of further modifications. Events such as excess feedwater, loss of normal feedwater, and steam generator tube rupture have led to significant primary system cooldowns. Each of these cooldown transients occurred concurrently with a relatively high primary system pressure. Consideration of these and other postulated cooldown events has drawn attention to the impact of operator action and control system effects on reactor vessel PTS.A methodology, which couples event sequence analysis with probabilistic fracture mechanics analyses, was developed to identify those events that are of primary concern for reactor vessel integrity. Operating experience is utilized to aid in defining the appropriate event sequences and event frequencies of occurrence for the evaluation.Once the specific event sequences of concern are identified, detailed thermal-hydraulic and structural evaluations can be performed to determine the conditions required to minimize the extension of postulated flaws or enhance flaw arrest in the reactor vessel. This paper addresses key aspects of the thermal-hydraulic and fracture mechanics analyses of the reactor vessel. The effects of incomplete mixing of safety injection flow in the primary cold leg and vessel downcomer and the application of warm prestressing are emphasized. The results of these analyses are being used to define further modifications in vessel and plant system design and to operating procedures.Previous design considerations that have evolved as a result of reactor vessel integrity evaluations are mentioned. These include the development of realistic design analysis tools and selection of plant system modifications. Modifications that are being developed or are under consideration are also mentioned. These include vessel fluence reductions, additional modifications to operating procedures, increased use of probabilistic event sequence and fracture mechanics analysis methods, enhanced material fracture toughness, and reductions in the severity or frequency of occurrence of dominant reactor vessel PTS transients.     

Phospholipid membrane stabilization by dimethylsulfoxide and other inducers of Friend leukemic cell differentiation

A large number of low molecular weight polar cryoprotective agents have recently been found to induce erythroid differentiation of Friend leukemic cells in vitro. The effect of these agents on membrane fluidity in phospholipid vesicles was studied by determining the solid-to-liquid crystalline phase transition using differential scanning calorimetry. Some of the inducing agents studies were found to raise the normal transition temperature (Tc) by a few degrees. All of these agents were found to produce a separate transition at a much higher temperature. Changes in the head group of the phospholipid, the pH, the presence of divalent cations, and the addition of other membrane-active compounds were found to significantly influence the inducing agent's effects on the Tc of phospholipid membranes. The ability of the different agents to produce a new transition at a high temperature was found to correlate well with their ability to induce Friend leukemic cell differentiation. The possible mechansims of action of the chemical inducers, and the significance of the observed membrane effects on differentiation and malignancy are discussed. It is concluded that inducing agents decrease the fluidity and stabilize phospholipid membranes, and that their effects in cell differentiation might be initiated by a similar change in the properties of cell membranes.     

Endotoxic activity of cell-free rumen fluid from cattle fed hay or grain

The cell-free rumen fluid from cattle fed hay or grain exhibited the following biological characteristics which strongly suggest the presence of endotoxin or a toxic principle similar to endotoxin of gram-negative bacteria: proved lethal to mice when injected with actinomycin D; proved extremely lethal to chick embryo; induced biphasic pyogenic response in rabbits; enhanced susceptibility to bacterial infection in mice; evoked positive epinephrine skin reaction in rabbits and phenol-water or aqueous ether proved lethal to mice and chick embryos. A quantitative difference in concentrations of endotoxin was observed on LD50 in mice and chick embryos and response to the epinephrine skin test in rabbits. Cell-free rumen fluid of grain-fed cattle contained at least twice as much endotoxin as that of hay-fed cattle. Endotoxin in cell-free rumen fluid and in higher concentration in cattle fed grain than in those fed hay support the hypothesis that rumen bacterial endotoxins may participate in the pathogenesis of diseases associated with high grain feeding such as lactic acidosis and the sudden-death syndrome.