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Biomedical subjects

B Lane

Publications and source records attributed to B Lane.

At least 127 records · Page 7Linked to original sources
PubMed1984

A chemoattractant receptor on macrophages exists in two affinity states regulated by guanine nucleotides.

The binding characteristics of the oligopeptide chemoattractant receptor on guinea pig macrophages and macrophage membrane preparations were characterized using detailed binding studies and computer analysis. Viable macrophages bound the radiolabeled chemoattractant N-formyl-methionyl-leucyl-[3H]phenylalanine with single dissociation constant (KD) of 18.4 +/- 4.6 nM with 15,300 +/- 1,800 sites per cell. Binding data from membrane preparations indicated the presence of two classes of binding sites with KD of 1.5 +/- 0.4 nM and 25.5 +/- 11.0 nM. Approximately 23% of the receptors were in the high affinity state. In the presence of added guanine nucleotide di- or triphosphates, the high affinity receptors in the membrane preparations were converted to low affinity states with no change in the total receptor number. Nonhydrolyzable derivatives of GTP were most potent in converting the receptor from its high to low affinity state. These data suggest that the affinity state of the oligopeptide chemoattractant receptor in macrophages is regulated by guanine nucleotides and GTPase, implying that the transduction mechanisms of this receptor may be controlled by a guanine nucleotide regulatory unit.

Animals↗
PubMed1984

Induction of hepatic protein synthesis by a peptide in blood plasma of patients with sepsis and trauma.

Accelerated release of amino acids from muscle and their uptake for protein synthesis by liver and other visceral tissues are characteristic of trauma or sepsis. Experimentally, this response is induced by interleukin-1 (IL-1) generated by activated macrophages in vitro. However, IL-1 has not been demonstrated in human blood. A small 4000-dalton peptide recently isolated from plasma of patients with sepsis and trauma induces muscle proteolysis and is called "proteolysis-inducing factor" (PIF). To test whether this agent has the ability also to induce hepatic protein synthesis, a series of animal experiments and clinical observations were undertaken. The structural and secretory (acute-phase reactants) in vitro protein synthesis in livers of normal rats injected intraperitoneally with IL-1 or PIF was significantly greater than that of normal rats or those injected with Ringer's lactate (p less than 0.01). In patients with sepsis and trauma the central plasma clearance rate of amino acids, a measure of visceral (principally hepatic) amino acid uptake, was elevated and correlated with the rates of protein synthesis in incubated liver slices obtained by biopsy at operation from the same patients (p less than 0.05). Both in vivo measured central plasma clearance rate of amino acids and in vitro measured hepatic protein synthesis correlated with plasma levels of PIF in the same patients (p less than 0.01 and p less than 0.05, respectively). We conclude that since PIF, and not IL-1, is present in human plasma and both are produced by activated macrophages, PIF seems to be the stable circulating cleavage product of IL-1, which induces not only muscle proteolysis but also hepatic protein synthesis, principally in the form of acute-phase reactants during infection and other states in which inflammation is present.

Amino Acids↗
PubMed1983

Dynamic preoperative assessment of cardiac reserve in elective aortic surgery.

Myocardial infarction accounts for over 50 per cent of mortality following elective abdominal aortic surgery. Previous history of ischaemic heart disease and abnormal ECGs, common in vascular patients, are unreliable parameters for predicting myocardial response to stress. Exercise ECGs are often valueless, as claudication may mask myocardial insufficiency. Myocardial performance was studied preoperatively in 29 consecutive patients undergoing elective aortic bifurcation grafting, using a Swann-Ganz catheter to measure the rise in pulmonary artery wedge pressure (PAWP) produced by rapid intravenous infusion of plasma (200-400 ml). A Frank-Starling Curve was obtained by plotting LVSWI against PAWP. Two important values were obtained: (a) 'Upslope' or gradient of the ascending portion of the curve. Low values identify patients most at risk from cardiac complications. Six patients who suffered from postoperative cardiac complications had a mean 'upslope' value of 1.568 +/- 0.681 (1 s.e.m.), whereas the 23 who did not, had a mean value of 7.094 +/- 0.745 (1 s.e.m.), a significant difference (P less than 0.001); (b) 'PAWPmax', the ventricular filling pressure above which work output dropped. Infusion beyond this may precipitate pulmonary oedema. PAWP was observed at levels greater than PAWPmax in all 6 patients who developed either pulmonary oedema or myocardial infarction. The myocardial performance curve can reliably identify high risk patients and permit control of intravenous therapy within individual safety limits, thereby preventing pulmonary oedema.

Adult↗
PubMed1983

Role of steroids in secretion--modulating effect of triamcinolone and estradiol on protein synthesis and secretion from the rat exocrine pancreas.

Following adrenalectomy of male rats, or adrenalectomy and ovariectomy of females, there was marked depletion of zymogen granules in acinar cells of the pancreas. Within 9 h after treatment with either triamcinolone or 17 beta-estradiol, complete restoration of these secretory vesicles was observed. This repletion was not inhibited by actinomycin-D. Supernatant fractions (100,000 g, 60 min) of rat pancreas, from both normal and surgically altered animals, contained proteins that bound [3H]-triamcinolone and [3H]-estradiol, suggesting that the action of these hormones is exerted directly on the pancreas. Binding of both steroid hormones required the presence of an additional coligand referred to as accessory factor. In addition, the binding proteins for [3H]-triamcinolone and [3H]-estradiol eluted in similar positions after Sephadex G-200 and CM Affi-gel Blue chromatography. It is uncertain, however, whether a single protein binds both steroid hormones since they had different binding isotherms. Scatchard analysis of binding of [3H]-estradiol yielded a single straight line of negative slope from which it was calculated that there were about 4.4 pmol of binding sites per mg protein, having an average apparent Kd of about 5 X 10(-8) M. Similar analysis of the data for [3H]-triamcinolone yielded a straight line of zero slope indicating nonsaturable binding of hormone at concentrations as high as 10 microM. Since both [14C]-L-leucine incorporation into protein and amylase secretion were affected markedly by the steroid-hormonal status of the animal, it is presumed that steroid-bound complexes in acinar cells of the pancreas modulate synthesis and secretion of protein.

Adrenalectomy↗
PubMed1983

Computed tomography of axial myopia.

Computed tomography (CT) is the primary imaging modality for evaluation of an orbital mass presenting as proptosis. Axial myopia is a benign cause of unilateral proptosis frequently encountered by the ophthalmologist. Identification of this condition by CT avoids additional investigation of the cause of the proptosis.

Exophthalmos↗
PubMed1983

Digital subtraction cerebral angiography by intraarterial injection: comparison with conventional angiography.

For 4 months, a prototype digital subtraction system was used to obtain images of the cerebral vasculature after intraarterial contrast injections. In 12 instances, the intraarterial injections were recorded with both a digital subtraction unit and conventional direct magnification film-screen system. The digital subtraction and conventional film subtraction images were compared and graded for quality and information content by three skilled observers. In addition, quantitative measurements of contrast-detail performance and spatial resolution were obtained on both the digital system and the screen-film imaging chain. In a clinical setting, both the digital subtraction and conventional film-screen systems provided similar quality images and angiographic information. Contrast-detail curves demonstrated that digital subtraction angiography outperformed conventional film technique for low-contrast objects. Digital subtraction angiography also reduced the time required to obtain the angiogram, markedly reduced film cost, and lowered the contrast agent burden.

Adolescent↗
PubMed1982

Sweat gland carcinoma with hypercalcemia.

A case is presented in which a large recurrent malignant tumor of the thigh of probable sweat gland origin is associated with hypercalcemia. The tumor invaded the periosteum of the pubis. Hypercalcemia subsided following hemipelvectomy and the patient has remained asymptomatic since 1977.

Adult↗
PubMed1982

Myelography in lumboperitoneal shunts.

Lumboperitoneal shunts have become more prevalent since the introduction of Silastic tubing. One disadvantage of this procedure is the difficulty in obtaining a subsequent myelogram. In the presence of a lumboperitoneal shunt, it may be advisable to modify the usual technique in obtaining a satisfactory myelogram. Use a low lumber puncture for a lumbar study, a C1-2 puncture for the cervical and thoracic regions, and use metrizamide to avoid the potential problem of Pantopaque in the peritoneal cavity.

Cerebrospinal Fluid Shunts↗
PubMed1982

Granular cell variant of neurofibromatosis: ultrastructure of benign and malignant tumors.

A case of neurofibromatosis with a metastasizing malignant tumor is presented. The benign lesions were identified by light microscopy as neurofibromas containing granular cells typical of granular cell tumors. The malignant tumor was classified as a malignant granular cell tumor. Ultrastructural studies demonstrated common histogenetic and subcellular features of the benign and malignant tissues. The case is the first reported in which granular cells are seen in the lesions. The typical granular cell morphologic features of the malignant lesion support the concept of Schwann cell derivation of this group of tumors.

Adult↗
PubMed1982

Role of tumor cell membrane-bound serine proteases in tumor-induced target cytolysis.

The tumor-induced marrow and red blood cell cytolysis assays have been used to explore the mechanism of cancer cell destruction of normal cells. Previously, we suggested that tumor-induced cytolysis was caused by tumor cell membrane-bound serine proteases. In this study, we have shown that concentrations of the broad-spectrum serine protease inhibitor diisopropylfluorophosphate that did not inhibit tumor cell DNA and protein synthesis completely abrogated tumor-induced red blood cell cytolysis. In addition, tumor cell membranes isolated by differential and sucrose density gradient centrifugation and characterized by electron microscopy and enzyme marker analysis were cytolytic for rat 59Fe-labeled red blood cells. The specific activity expressed as release index (%) per microgram of protein was 1.620 for the tumor cell membrane preparations as compared to 0.002 for intact Walker 256 tumor cells. Tumor cell membranes solubilized in Triton X-100 had activity in the p-toluenesulfonyl-L-arginine methyl ester assay for trypsin-like enzymes and the N-benzoyl-L-tyrosine ethyl ester assay for chymotrypsin-like enzymes. The enzyme activities demonstrated in these assays could be inhibited by N-alpha-p-tosyl-L-lysine chloromethyl ketone HCl and L-1-tosylamide-alpha-phenyl-ethyl chloromethyl ketone, respectively. Using [3H]diisopropylfluorophosphate affinity labeling of the tumor cell membrane proteins followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, we have identified membrane-bound serine protease(s) that appear to be responsible for tumor-induced marrow and red blood cell cytolysis.

Animals↗
PubMed1981

Risk factor analysis of intraventricular hemorrhage in low-birth-weight infants.

Sixty of 63 newborn infants weighing less than 1,250 gm, admitted consecutively to the Intensive Care Nursery during a 15-month period, were prospectively investigated for the incidence of intraventricular hemorrhage by early computerized tomography or by autopsy. Nineteen of the 60 infants had evidence of IVH. The incidence of IVH was correlated with the presence of possible neonatal, obstetrical, asphyxial, or therapeutic risk factors. There was a significant difference in only one of the risk factors: birth outside the perinatal center. Fifteen of 27 outborn infants (56%) developed IVH, whereas only four of 33 inborn infants (12%) developed IVH (P less than 0.001). There were no statistically significant differences in maternal obstetrical risk factors, infant risk factors, or indices of birth asphyxia in the inborn compared with the outborn infants. However, perinatal therapeutic risk factors differed between the two groups. Outborn infants were less likely to have received betamethasone (P less than 0.001), were less likely to have their arterial blood gases monitored and stabilized during the first 20 minutes after birth (P less than 0.001), and were given more bicarbonate (P less than 0.001) and more boluses of fluid intravenously (P less than 0.02). The risk of IVH in very low birth-weight infants may be significantly decreased by therapeutic factors at birth. Maternal transport to a perinatal center and intensive neonatal resuscitation may contribute to decreasing the incidence of intraventricular hemorrhage.

Cerebral Hemorrhage↗