Genetic approaches to study export of LamB to the outer membrane

We are studying the molecular mechanism of cellular protein localization. The availability of genetic techniques, such as gene fusion in Escherichia coli, has made this subject particularly amenable to study in this prokaryote. We have constructed a variety of strains in which the gene coding for an outer membrane protein is fused to the gene coding for a normally cytoplasmic enzyme, beta-galactosidase. The hybrid protein produced by such strains retain beta-galactosidase activity; this activity serves as a simple biochemical tag for studying the localization of the outer membrane protein. In addition, we have exploited phenotypes exhibited by certain fusion strains to isolate mutants that are altered in the process of protein export. Genetic and biochemical analyses of such mutants have provided important insights into the mechanism of protein localization.

Analysis of human cytomegalovirus nucleoprotein complexes

When chromatin was isolated from cells infected with human cytomegalovirus, the virus DNA remained with the chromatin fraction. If deproteinized virus DNA was added to either isolated nuclei or chromatin, the DNA was lost during the chromatin isolation. When isolated chromatin from cytomegalovirus-infected cells was banded in isopycnic metrizamide gradients, a single peak with a density of 1.18 g/cm3 was present. Analysis of this peak in isopycnic neutral CsCl gradients indicated that it contained both human cytomegalovirus and human embryonic lung cell DNAs. When infected nuclei were treated with micrococcal nuclease, 11S subunit particles which cosedimented with cell nucleosomes and contained virus DNA were isolated.

Effects of water supplementation on physiological jaundice in breast-fed babies

The effect of water supplementation in normal, term, breast-fed babies with physiological jaundice was studied. Water supplementation was given to 120 babies and 55 received no extra fluids. There was no significant difference between the two groups when peak serum bilirubin levels and incidence of phototherapy were compared.

A signal sequence is not sufficient to lead beta-galactosidase out of the cytoplasm

Escherichia coli strains have been constructed in which lacZ, the gene for the cytoplasmic enzyme beta-galactosidase, is fused to lamB, the gene for an outer membrane protein. One such strain produces a beta-galactosidase which remains cytoplasmic even though it possesses the complete signal sequence of the lamB protein precursor at the amino-terminal end.

The effect of intracerebroventricular administration of methionine-enkephalin on the stress-induced secretion of corticosterone in mice

Ether stress or intracerebroventricular (i.c.v.) administration of saline, met-enkephalin, or naltrexone raised plasma corticosterone levels in mice. The response to ether stress was abolished by a preceding ether stress or by pretreatment with i.c.v. saline or naltrexone. However, following i.c.v. met-enkephalin, plasma corticosterone was significantly elevated by ether stress, the effect being blocked by simultaneous injection of met-enkephalin and naltrexone. Met-enkephalin appears to prevent fast-feedback inhibition of the hypothalamus-pituitary-adrenal system.

Naproxen in juvenile chronic polyarthritis

Naproxen at 10 mg per kg body weight was compared with aspirin at 80 mg per kg body weight in children suffering from juvenile chronic polyarthritis. It was found to be as effective as aspirin, with certainly no more and possibly fewer gastrointestinal side effects. A long-term tolerance study up to 12 months confirmed that naproxed was a satisfactory nonsteroidal anti-inflammatory drug in the management of various types of juvenile chronic arthritis.

The effects of opioid drugs and of lithium on steroidogenesis in rat adrenal cell suspensions

1. The effects of opioid drugs and of Na+ replacement on steroidogenesis in rat adrenal cell suspensions were investigated. 2. In medium containing normal Na+ (156 mM), opioid antagonists but not opioid agonists reduced the steroidogenic response to adrenocorticotrophic hormone1-24 (ACTH1-24) but not to dibutyryl adenosine 3',5' cyclic monophosphate (db cyclic AMP). 3. Replacement of 50% Na+ in the medium by choline had no effect on steroidogenesis, but further reductions in Na+ content reduced the steroidogenic activity of both ACTH1-24 and db cyclic AMP. 4. In 50% Na+ medium both opioid agonists and antagonists inhibited ACTH1-24 induced steroidogenesis. 5. Addition of therapeutic concentrations of lithium to otherwise normal medium inhibited the steroidogenic response to ACTH1--24 but not to db cyclic AMP. 6. The selective inhibition of ACTH1--24-induced steroidogenesis by opioid drugs suggests some similarity between the opioid and ACTH receptors. 7. The relevance of the potent inhibitory effect of lithium to its therapeutic actions is discussed.

The gravity suit: a major advance in management of gynecologic blood loss

We have used the gravity suit (G-suit) to stabilize patients in shock as a result of ruptured ectopic pregnancies. Four patients presenting in shock were carefully studied with serial vital signs, fluid replacement, and blood loss before and after application of the G-suit. These studies were continued through surgery and the removal of the G-suit. The G-suit improved vital signs, increased peripheral organ and limb perfusion, and decreased blood loss in all cases.

The effects of opiate receptor agonists and antagonists on the stress-induced secretion of corticosterone in mice

1 Intraperitoneal administration of normorphine, morphine or naloxone or exposure to ether vapour for 1 min, elevated plasma corticosteroid concentrations in mice. 2 Injection of saline or exposure to ether vapour rendered mice less sensitive to a subsequent exposure to ether vapour 15 min later. 3 Treatment with normorphine (50 mg/kg) potentiated the corticosteroid response to ether stress whilst pentazocine (20 mg/kg), naltrexone (10 mg/kg), morphine (24 mg/kg), levorphanol (20 mg/kg) and naloxone (50 mg/kg) prevented the stress-induced elevation of plasma corticosteroids. 4 Both naloxone and morphine inhibited the potentiation by normorphine of the response to ether, the dose of naloxone required being higher than that for inhibition of normorphine analgesia. 5 It is concluded that endogenous opioid peptides may be involved in the control of the response to ether stress in mice.

The premature breech: trial of labor or cesarean section?

Sixty-six premature breech deliveries were studied retrospectively. Forty-eight patients were permitted a trial of labor, 47 of whom ultimately delivered vaginally. Eighteen patients underwent cesarean section as soon as possible after their arrival at the delivery suite. When Apgar scores, perinatal mortality rates, cord prolapse, and entrapment of the aftercoming head are considered, cesarean section is probably the safer course of management for the patient with a footling breech infant, especially when the infant weighs 1500 g or less. However, the data indicate that a trial of labor can be safely undertaken in the presence of a premature frank or complete breech presentation.

Evaluation of a routine anaerobic subculture of blood cultures for detection of anaerobic bacteremia

The value of a routine 48-h anaerobic subculture of blood cultures was assessed in our laboratory over a 4-month period. Excluding presumed contaminants, anaerobes represented 51 (6.9%) of the total number of 734 positive cultures. Sixteen isolates (all Bacteroides) from six patients were detected by the anaerobic subculture. All but one of these were also detected macroscopically. Excluding the one isolate, the routine anaerobic subculture hastened the identification of anaerobic organisms by only 1 day in two patients. We conclude that a routine anaerobic subculture is not indicated for the detection of anaerobic bacteremia.

Blue naevus of the cervix: report of two cases and review of the literature

Two cases are described of blue naevi occurring in the uterine cervix. These showed a histological appearance identical to that seen in the commoner cutaneous examples. Electron microscopy of both lesions showed the presence of melanosomes in the dendritic cells. No Schwann cell elements were identified. Previous reports of cases are reviewed and discussed.

Meconium passage: a new classification for risk assessment during labor

The significance of MSAL as a sign of fetal distress is controversial. To better assess this condition, we present a classification of MSAL based on the timing and quantity of meconium passed and divided into early light, early heavy, and late passage of MSAL. By means of this classification with a problem-oriented risk assessment system, 2,933 pregnancies were prospectively evaluated during labor. The incidence of meconium passage was 22 per cent, of which early light constituted 53.6 per cent, early heavy 25.2 per cent, and late passage 21.2 per cent. Early heavy MSAL is associated with increased fetal and neonatal morbidity and death, and with a number of antecedent obstetric problems. Late passage of MSAL encountered no perinatal losses, but is associated with increased neonatal morbidity occurring late in labor. Early light MSAL, constituting over half of all our meconium group of patients, is not associated with any increased intrapartum or neonatal morbidity or death. This classification of MSAL is an effective tool for risk assessment during labor.

[Use of arterio-venous fistulas for hemodialysis in children (author's transl]

From September 1977 till December 31st 1977, 21 arterio-venous fistulas were created in 18 children aged 6 to 15 years. Four early failures occured. The probability of fistula survival is 93% at 2 years for children treated only with hemodialysis. At the end of this same period of time, 62% of patients submitted to a combined treatment of hemodialysis followed by kidney transplantation have a functioning fistula. Overgrowth of the involved extremity, infection episodes and cardiac failure were not observed. One arteriovenous fistula is still functioning after 8 years.

Cleavage planes in the envelope of Aquaspirillum bengal

The cell surface of Aquaspirillum bengal was devoid of superficial wall structure. When cells were freeze-cleaved and etched, multiple fracture planes through the cell envelope were exposed, which was unusual for an aquaspirillum. These included both convex and concave surfaces and they are compared with those of other gram-negative bacteria.

Metabolsim of apoB and apoC lipoproteins in man: kinetic studies in normal and hyperlipoproteininemic subjects

The kinetics of apolipoproteins B and C were studied in 14 normal and hyperlipoproteinemic subjects after injection of exogenously (125)I-labeled very low density lipoprotein (VLDL) particles. Plasma radioactivities of apoB and apoC were determined over a period of 4 days in VLDL (d < 1.006) and total radioactivity in intermediate (IDL) (1.006 < d < 1.019), low (LDL) (1.019 < d < 1.063), and high (HDL) (1.063 < d < 1.21) density lipoproteins. The data were analyzed by the use of a model, developed mostly from these data, with the following results. The VLDL particle undergoes a series of incremental density changes, most likely due to a number of delipidation steps, during which apoB stays with the particle until the density reaches the IDL range. There is, however, a loss of apoC associated with these delipidation steps. In our normal subjects, all IDL apoB eventually becomes LDL. In our hyperlipemic subjects some of the apoB on IDL is also degraded directly. The apoC lost by VLDL and IDL recycles to HDL, and most of it is picked up again by newly synthesized VLDL. There is a slowdown of the stepwise delipidation process in all hyperlipemic individuals studied. Three additional features became apparent in the type III subjects. First, there is a significant increase (a factor of 2 compared to normal) in the apoB synthesis rate by way of VLDL; second, there is an induced direct apoB synthesis pathway by way of IDL (and/or LDL); third, a bypass of the regular stepwise VLDL delipidation pathway is induced by which VLDL particles lose apoC but none of their apoB, thereby forming a new particle with metabolic properties similar to LDL, but with a density still in the VLDL density range. Two type III patients treated with nicotinic acid and clofibrate showed a sharp decrease in their VLDL apoB synthesis rates. This was somewhat compensated by an increased IDL apoB synthesis rate. A type I patient on a medium chain triglyceride diet also showed a number of metabolic changes, including reduced VLDL apoB synthesis and the induction of considerable IDL and/or LDL apoB synthesis.

Yellow-brown spindle bodies in mesenteric lymph nodes: a possible relationship with melanosis coli

Four cases are described in which spindle-shaped, yellow-brown bodies were seen in the mesenteric lymph nodes of patients with melanosis coli. A comparison of the staining reactions and ultrastructural appearances of the spindle bodies and melanosis pigment suggest that they are related within the broad group of lipofuscins and that the spindle bodies are formed as a result of coalescence of lysosomes containing the pigment.

High density lipoprotein metabolism in man

The turnover of (125)I-high density lipoprotein (HDL) was examined in a total of 14 studies in eight normal volunteers in an attempt to determine the metabolic relationship between apolipoproteins A-I (apoA-I) and A-II (apoA-II) of HDL and to define further some of the determinants of HDL metabolism. All subjects were first studied under conditions of an isocaloric balanced diet (40% fat, 40% carbohydrate). Four were then studied with an 80% carbohydrate diet, and two were studied while receiving nicotinic acid (1 g three times daily) and ingesting the same isocaloric balanced diet. The decay of autologous (125)I-HDL and the appearance of urinary radioactivity were followed for at least 2 wk in each study. ApoA-I and apoA-II were isolated by Sephadex G-200 chromatography from serial plasma samples in each study. The specific activities of these peptides were then measured directly. It was found that the decay of specific activity of apoA-I and apoA-II were parallel to one another in all studies. The mean half-life of the terminal portion of decay was 5.8 days during the studies with a balanced diet.Mathematical modeling of the decay of plasma radioactivity and appearance of urinary radioactivity was most consistent with a two-compartment model. One compartment is within the plasma and exchanges with a nonplasma component. Catabolism occurs from both of these compartments. With a balanced isocaloric diet, the mean synthetic rate for HDL protein was 8.51 mg/kg per day. HDL synthesis was not altered by the high carbohydrate diet and was only slightly decreased by nicotinic acid treatment. These perturbations had effects on HDL catabolic pathways that were reciprocal in many respects. With an 80% carbohydrate diet, the rate of catabolism from the plasma compartment rose by a mean of 39.1%; with nicotinic acid treatment, it fell by 42.2%. Changes in the rate of catabolism from the second compartment were generally opposite those in the rate of catabolism from the plasma compartment, suggesting that these two catabolic pathways may be reciprocally regulated.

Analysis of isomeric impurities in a synthesis of the novel anti-inflammatory drug, benoxaprofen

Gas-liquid chromatographic procedures are described for the determination of isomeric impurities in rho-chlorobenzoyl chloride and the intermediates, 2-(rho-nitrophenyl)-proprionitrile and 2-phenylpropionitrile, in a ten-stage synthesis of benoxaprofen, 2-(rho-chlorophenyl)-alpha-methyl-5-benzoxazoleacetic acid.

Separation of benefin and trifluralin by gas chromatography using a liquid crystal column

Benefin (N-[n-butyl]-N-ethyl-2,6-dinitro-alpha, alpha, alpha-trifluoro-p-toluidine) and trifluralin (2,6-dinitro-N,N-di-n-propyl-alpha, alpha, alpha-trifluoro-p-toluidine) (Figure 1) are isomeric preemergent herbicides (1,2). As they possess different activities, their use necessitates the development of a routine analytical method which differentiates between them. The separation of these isomers by gas-liquid chromatography (GLC) using conventional column packings has proved extremely difficult. Two partly successful separations have been previously reported to date. A partial separation was obtained using a Durapak-Carbowax 400/Poracil C column (3) and a complete separation using a column packed with a monomolecular layer of Carbowax 20M on Chromosorb W (4). Unfortunately, this latter column has a very limited life and the analysis time is 25 minutes. This paper reports a rapid and reproducible separation of benefin and trifluralin using a liquid crystal stationary phase.

Multiple pigmented naevi in an albino

A case of pigmented naevi arising in an albino is described. The histological appearance of a naevus is described in the nature of the pigment discussed.

Rhodopsin in the rod outer segment plasma membrane

Isolated frog retinas were incubated in vitro with a 4-h pulse of [3H]leucine, then chased for 32 h with a nonradioactive amino acid mixture. At the end of the incubation, light and electron microscope autoradiograms were prepared from some of the retinas. The autoradiograms revealed: (a) intense radioactivity in the basal disks of the rod outer segments, (b) diffuse label evenly distributed throughout the rod outer segments, and (c) a high concentration of label in the entire rod outer segment plasma membrane. Incubation under identical conditions, but with puromycin added, significantly inhibited the labeling of all of these components. To identify the labeled proteins, purified outer segments from the remaining retinas were analyzed biochemically by SDS disc gel electrophoresis and gel filtration chromatography. SDS gel electrophoresis showed that about 90% of the total rod outer segment radioactivity chromatographed coincident with visual pigment, suggesting that the radiolabeled protein in the plasma membrane is visual pigment. Gel filtration chromatography demonstrated that the radiolabeled protein co-chromatographed with rhodopsin rather than opsin, and that the newly synthesized visual pigment is both the basal disks and the plasma membrane is present in the native configuration.

The adenosine triphosphate content and lactic acid production of guinea-pig skin after mild heat damage

The depletion of adenosine triphosphate in skin after mild thermal injury is not large enough to be accounted for by loss of oxidative respiration. Measurement of lactic acid production by skin suggest that glycolysis is less sensitive to heat damage than is oxygen uptake. It is therefore likely that glycolysis makes a large contribution to the relatively high levels of ATP persisting in heat damaged skin.

The succinic dehydrogenase and cytochrome c oxidase activities of guinea-pig skin after mild heat damage

Succinic dehydrogenase and cytochrome c oxidase activities of guinea-pig ear skin were found to be less sensitive than oxygen uptake to mild heat damage. It therefore appears that the failure of oxygen uptake following thermal injury is not directly due to inactivation of the enzymes of the respiratory chain.

Effects of atmosphere of incubation and of routine subcultures on detection of bacteremia in vacuum blood culture bottles

Studies comparing isolation rates of bacteria and yeasts from vented and unvented vacuum blood culture bottles containing soybean-casein digest broth showed significantly more frequent and more rapid recovery of Candida and Pseudomonas from the vented bottle and no other statistically significant differences between the two. Subculture of bottles on the day of their collection was shown to accelerate recovery of 48% of positive cultures by day 1. A second subculture of known positive cultures yielded additional organisms in 1.5% of cultures.

Effects of thrombin treatment of preparations of factor VIII and the Ca2+-dissociated small active fragment

When human, canine, or bovine factor VIII preparations are chromatographed on 4% agarose at ionic strength 0.2, the factor VIII activity elutes as a single peak in the void volume with slight tailing. Incubation of such preparations with dilute (0.01 U/ml) highly purified thrombin results in some activation of factor VIII. Chromatography of such incubation mixtures, under the same conditions as before, results in elution of two peaks of factor VIII activity one in the void volume and one much later with marked tailing. The void volume peak has most of the protein and some factor VIII activity. These void volume fractions also contain all the von Willebrand factor activity of thrombin-treated bovine preparations. Longer treatment with thrombin, or treatment with stronger thrombin, appears to shift much more of the procoagulant activity to the later eluting peak. Also, when the peak of factor VIII activity, found in the void volume after thrombin treatment, was again incubated with dilute thrombin, an increase in factor VIII activity occurred. Chromatography of this incubation mixture demonstrated only a small amount of activity in the void volume, while the bulk of the activity was present in the second peak. On the other hand, thrombin treatment of factor VIII activity from peak 2 caused a rapid decline of activity instead of a further increase. It is proposed that the residual factor VIII activity found in the void volume represents unreacted factor VIII, while the late eluting peak represents thrombin-activated material that is of smaller apparent size. The late eluting peak differs from the small active factor VIII fragment obtained by Ca2+ dissociation, as the latter can be activated by thrombin. A similar set of experiments was performed using ultracentifugation of bovine factor VIII preparations on sucrose density gradients. Results of these experiments agreed completely with those obtained with get chromatography. Preparations made from human hemophilic plasma, by the procudure employed in the purification of human factor VIII, were also incubated with thrombin and chromatographed. von Willebrand factor was again found only in the void volume fractions, but there was no factor VIII activity in any fractions eluted. In other control experiments, activated and unactivated factor VIII fractions did not clot fibrinogen and contained no assayable factor IX or X. The thrombin-modified factor VIII of small size was inactivated by both a naturally occurring human inhibitor to factor VIII and the gamma globulin fraction of a rabbit antisera produced against the calcium-dissociated small active factor VIII fragment.

Recovery of yeast from vented blood culture bottles

Rates of isolation of yeasts from blood cultures were significantly enhanced by venting vacuum blood culture bottles in studies of both stimulated and patients' blood cultures; however, the time interval to detection of positivity of yeasts in the clinical studies was significantly (P less than 0.01) shorter in a vented bottle with biphasic brain heart infusion medium than in a vented bottle with soybean-casein digest broth. The mean time intervals to detection of positivity were 2.6 days in the former and 5.2 days in the latter.