Noncontact dipole effects on channel permeation. IV. Kinetic model of 5F-Trp(13) gramicidin A currents

Nonlinear least squares fitting was used to assign rate constants for the three-barrier, two-site, double-occupancy, single-filing kinetic model for previously reported current-voltage relations of (5F-Indole)Trp(13) gramicidin A and gramicidin A channels (, 75:2830-2844). By judicious coupling of parameters, it was possible to reduce the parameter space from 64 parameters to 24, and a reasonable fit consistent with other experimental data was obtained. The main features of the fit were that fluorination increased the rate constant for translocation by a factor of 2.33, consistent with a free energy change in the translocation barrier of -0.50 kcal/mol, and increased first-ion binding affinity by a factor of 1.13, primarily by decreasing the first-ion exit rate constant. The translocation rate constant was 5.62 times slower in diphytanoyl phosphatidylcholine (DPhPC) bilayers than in monoolein (GMO) bilayers (coupled for the four combinations of peptide and salt), suggesting a 44.2-mV difference in the projection of the interfacial dipole into the channel. Thus fluorination caused increased currents in DPhPC bilayers, where a high interfacial dipole potential makes translocation more rate limiting because the translocation barrier was reduced, and decreased currents in GMO bilayers, where ion exit or entry is rate limiting because these barriers were increased.

The genome organisation and taxonomy of Sugarcane striate mosaic associated virus

Sugarcane striate mosaic associated virus (SCSMaV) has slightly flexuous 950 nm x 15 nm filamentous particles and is associated with sugarcane striate mosaic disease in central Queensland, Australia. We report the full sequence of its RNA genome, which comprises 5 open reading frames representing the polymerase, movement function proteins encoded in a triple gene block and coat protein. Phylogenetic analyses based on either the full nucleotide sequence, the polymerase protein, or the coat protein all placed SCSMaV in an intermediate position between the genera Foveavirus and Carlavirus, but outside both genera. In addition, the absence of a sixth open reading frame excludes it from the genus Carlavirus, and the coat protein is approximately half the size of the type member for the genus Foveavirus. Although SCSMaV was most closely allied to Cherry green ring mottle virus by genome analysis, the two viruses are morphologically and biologically dissimilar. SCSMaV may therefore represent a new plant virus taxon.

Identification and management of intravagal parathyroid adenoma

Intravagal parathyroid adenomas are rare, with only three cases reported in the English literature. The objective of this report is to describe two additional patients with hyperfunctioning parathyroid glands found within the vagus nerve and to define the anatomy of this finding. Both patients presented with a history of persistent hyperparathyroidism despite multiple therapeutic interventions. A high cervical localization was established in both cases by selective venous sampling. In each patient successful removal of the intravagal parathyroid gland was achieved with subsequent resolution of calcium and parathyroid levels. Each adenoma was located within the vagus nerve below the level of the carotid bifurcation and was enucleated without sacrificing the vagus nerve. In our cases and those reported previously, the parathyroid glands were supernumerary, representing parathyroid tissue embryologically derived from the third branchial pouch. Exploration for hyperparathyroidism requires a complete, meticulous surgical dissection to identify all parathyroid glands and to search for possible accessory tissue in selected cases. Our experience and a review of the literature serve to emphasize that, although rare, intravagal parathyroid adenomas do occur. Examination of the vagus nerve should therefore be strongly considered when four normal glands are found, as intravagal adenomas appear to represent accessory ectopically located parathyroid tissue.

A randomised controlled trial of intravenous versus inhalational analgesia during outpatient oocyte recovery

To compare the efficacy and acceptability of conventional intravenous sedation with patient-controlled inhalational isodesox, 57 women undergoing outpatient oocyte recovery were randomly allocated to receive isodesox by face mask, while 55 women were given intravenous fentanyl and midazolam. Women's satisfaction with pain relief, peroperative pain, clouding of memory and the surgeons' assessment of operating conditions were evaluated. Thirty-eight women in the inhalation group (67%) and 41 (75%) women in the intravenous group were 'very satisfied' with their analgesia (p = 0. 41). The mean (SD) pain score in women given isodesox was 46.8 (34. 7), while in the intravenous group it was 34.1 (21.3) (p = 0.02). Oxygen saturation levels < 94% were recorded in one woman using isodesox and in 16 (29%) women given intravenous analgesia. Despite higher pain scores, in comparison with the conventional analgesia, patient-controlled isodesox offers a safer method of pain relief with comparable satisfaction rates.

To determine whether the temperature of 2% lignocaine gel affects the initial discomfort which may be associated with its instillation into the male urethra

OBJECTIVE

To determine whether the temperature of 2% lignocaine hydrochloride gel affects the initial discomfort during instillation into the male urethra.

PATIENTS AND METHODS

Sixty consenting men were randomized to receive 11 mL of 2% lignocaine hydrochloride gel (Instillagel, Farco-Pharma GmbH, Cologne, Germany) at 4 degrees C, 22 degrees C or 40 degrees C. The three groups were well matched for age and numbers of previous flexible cystoscopies. The gel was instilled by one operator and the patients were then immediately asked to score the pain on instillation using a 100-mm nongraphical visual analogue scale.

RESULTS

Compared with the control group (at 22 degrees C), there was a statistically significant reduction in pain score in the group receiving cold gel (Student's t-test, P<0.05).

CONCLUSION

The cooling of 2% lignocaine gel significantly reduced the initial discomfort associated with its delivery into the male urethra before any form of urethral instrumentation.

Characterization and evaluation of detoxification functions of a nontumorigenic immortalized porcine hepatocyte cell line (HepLiu)

Primary porcine hepatocytes (PPH) are currently used in research and therapeutic applications as the biological component of extracorporeal liver assist devices to overcome the shortage of human hepatocytes. However, their finite life span and typically rapid loss of functions limit their utility. An immortalized, nontumorigenic, highly differentiated porcine hepatocyte cell line was developed in our laboratory to resolve these disadvantages. PPH were transfected with simian virus 40 (SV40) T antigen under the control of the SV40 early promoter. From the established 69 clones, 23 clones displaying hepatocyte-like morphology were screened for diazepam metabolism. One clone, HepLiu D63, has been maintained in culture for > 2 years, through more than 60 passages and 240 divisions. Albumin protein, present in early passages, was lost at later passages, but albumin transcript still was detectable in later passages. Carbamoyl phosphate synthetase, a gateway enzyme of the urea cycle, was consistently detectable in HepLiu cells. Cytokeratin 18, a characteristic marker of primary hepatocytes, was detected by both immunofluorescent staining and Western blot in HepLiu cells. Furthermore, maintenance of P450 functions in HepLiu cells was evidenced by diazepam and 7-ethoxycoumarin metabolites measured by HPLC. Phase II conjugative function was measured as acetaminophen glucuronidation. P450 dealkylase was demonstrated microscopically by the conversion of a nonfluorescent substrate to a fluorescent product. Both Northern blot analysis and immunofluorescent staining showed SV40 T antigen expression in the nuclei of HepLiu cells. No tumor formation occurred when HepLiu cells were injected into severe combined immunodeficient (SCID) mice nor was the TAI (a tumor marker) mRNA expressed, even in later passages. This immortalized, nontumorigenic, highly functional cell line may provide a valuable tool for drug/toxicological studies, liver biologic regulation studies, and artificial liver support systems.

Endocrine patterns during aging in the common tern (Sterna hirundo)

Blood samples were taken from breeding common terns (Sterna hirundo) of known age during two successive breeding seasons to determine if plasma concentrations of estradiol, progesterone, androgen, and luteinizing hormone (LH) reflect the process of aging. Males and females were trapped and sampled once between laying of the first and the second eggs in the clutch. The transient capture and sampling did not disrupt incubation or the timing of the subsequent oviposition. Ages ranged from 2 to 21 years, with most in the range 4-11 years. There was a strong inverse correlation (P < 0.0001) between age and laying date in both females and males, with older birds nesting earlier in the season. Plasma LH levels increased (P < 0.005) among mature (>5 year) females. Plasma progesterone and E2 were positively correlated with each other among mature females, but did not change in an age-dependent manner. In males, plasma progesterone levels showed no age-related changes. However, maturing (3-5 year) males showed increasing plasma androgen levels (P < 0.01); mature males showed no change with age. Plasma LH levels were correlated with androgen levels in both maturing and mature males. Plasma progesterone declined with age in maturing males (P < 0.001). These data provide evidence for changing endocrine status with age, but the patterns differ for younger individuals (</=5 year) and mature birds. It appears that in younger individuals, nesting experience and maturity of the pair affect reproductive performance and endocrine status. Individual variability was high for all hormones, possibly masking age-related changes. Only breeding individuals were sampled at all ages, although the proportion of the population that continues to reproduce may decline as the birds age. In summary, common terns continue to breed successfully until at least age 21 years and these individuals maintain relatively stable endocrine status during aging. Although there was some indication of declines in estradiol and androgens among the oldest birds (16-21 years), these declines were not statistically significant and were manifested in only a small fraction (<4%) of the breeding population.

Life Options Patient Opinion Study identifies keys to a long life for dialysis patients

Results of a recent survey of 31 people on dialysis show that, initially, most of them had no real expectation of living a long life when they started treatment. How and why have their perceptions changed? What can providers and other patients learn from this Life Options Patient Opinion Study? For people on dialysis, rehabilitation means living long and living well, despite the challenges of kidney disease. The first step to successful renal rehabilitation is ensuring that the clinical prerequisites of anemia control, adequate dialysis, a well-functioning vascular access, and proper nutrition are in place. In addition, research indicates that people on dialysis are more likely to experience positive outcomes and better quality of life when they are informed about their disease and its treatments; have solid support systems; exercise regularly and remain active and productive, and engage in self-care. It is the combination of good clinical care plus rehabilitation management that can help dialysis patients return to active and fulfilling lives. In 1993 the Life Options Rehabilitation Advisory Council (LORAC) developed a comprehensive approach to renal rehabilitation, based on the "5E's:" Encouragement, Education, Exercise, Employment, and Evaluation. Since then, the 5E's have served as the basis for numerous activities of the Life Options Rehabilitation Program. The Patient Opinion Study examined the patient experience as a way to begin identifying the keys to a long life on dialysis.

Food consumption patterns of Inuit women

To evaluate nutrient intake and food consumption patterns of Inuit women of child-bearing age, a 24-hour diet recall and general health and food frequency questionnaire was administered to 688 Inuit women aged 15-44 in six isolated communities. Data were analyzed using the 1991 Canadian Nutrient File. Mean intakes of essential nutrients were expressed as percentages of Health Canada's 1990 Recommended Nutrient Intakes (RNI). Chi-square tests were used to determine relationships between categorical variables. Folacin intake ranged from 49% to 95% of the RNI in most communities (median = 76%) and was only 37% of the RNI for pregnant and 54% for lactating women. Mean calcium intake for pregnant and lactating women averaged 55% and 47% of the RNI, respectively. Average vitamin A intakes ranged from 26% to 87% of the RNI (median = 65%), with intake for pregnant Inuit women and lactating women 79% and 54% of the RNI, respectively. Country food was the major source of protein and iron, and store foods the major source of calories, calcium, folacin, and vitamin A. Low intakes of folacin, calcium, and vitamin A, especially among pregnant and lactating women, place Inuit women of childbearing age at risk. Women on social assistance are nutritionally vulnerable.

Perceived ownership in a community coalition

Coalitions are emerging as a force for change in many communities and offer the opportunity for broad community involvement in the planning and implementation of needed health promotion and health education services. Perceived ownership promotes greater participation by the community but efforts to systematically evaluate ownership are lacking. The aim of this study was to determine ownership of a local ElderCARE Coalition's activities and its health promotion program, Healthy WAY, as perceived by coalition members. Fifteen of the coalition members returned the questionnaire that included the Community Ownership Scale. As shown by mean scores, the agencies perceived as having the most influence or greatest perceived ownership were the university college of nursing and the community action programs. Coalition members represented a wide variety of roles and responsibilities as well as length of time in the coalition (1 month to 6 years). Responses to open-ended questions, analyzed by content analysis, supported the work of the coalition and identified the senior participants in the Healthy WAY program as being "enthusiastic" but also needing to be more "involved." Process measures are important indicators of how close coalitions are staying to their grassroots constituency. Implications for public health nurses include participating as partners in community coalitions and assisting coalitions in determining their sense of ownership and the need for change.

Cost effectiveness of EUS for preoperative localization of pancreatic endocrine tumors

BACKGROUND

Endoscopic ultrasonography (EUS) is highly accurate in the localization of small pancreatic tumors. We determined the cost effectiveness of EUS used early in the preoperative evaluation of pancreatic endocrine tumors.

METHODS

In a study with a case-control design, 36 patients (19 men, 17 women) who underwent preoperative EUS were matched retrospectively with 36 patients who underwent surgical exploration immediately before the introduction of EUS. The number, cost, and effectiveness of preoperative localization studies, days of hospitalization, and surgical and anesthesia times were assessed.

RESULTS

The EUS group had reduced charges for preoperative localization studies: $2620 versus $4846 per patient (p < 0.05), largely because of reductions in the number of diagnostic angiograms and venous sampling procedures performed. Surgical and total anesthesia times were decreased, as were the number of preoperative admissions for angiographic procedures. The cost-effectiveness ratio for the EUS group was $3144 per tumor localized compared with $5628 per tumor localized for the group treated before EUS became available (p < 0.05).

CONCLUSION

EUS is highly accurate in the localization of pancreatic neuroendocrine tumors and is cost effective when used early in the preoperative localization strategy. EUS decreased the need for additional invasive tests and avoided unnecessary morbidity and resource consumption. EUS should play a primary role in preoperative localization of pancreatic neuroendocrine tumors.

Parental anxiety before elective surgery in children. A British perspective

This study measures the anxiety levels in 100 parents of children scheduled for elective surgery at the Royal Aberdeen Children's Hospital. Anxiety levels were quantified using the Leeds scale for self-assessment of anxiety. Forty-two per cent of parents were significantly anxious. Mothers were identified as being more pathologically anxious than fathers. The 'anxious' parents were specifically more anxious about the surgery, anaesthesia, postoperative pain and treatment, and hospitalisation in general. All parents, whether identified as anxious or not, agreed on factors likely to reduce anxiety: pre-operative information from staff, being able to accompany their child to the operating theatre and being present at induction of anaesthesia.

Phospholipase D1 localises to secretory granules and lysosomes and is plasma-membrane translocated on cellular stimulation

Phospholipase D (PLD) activity has been implicated in the regulation of membrane trafficking [1,2], superoxide generation and cytoskeletal remodelling [3,4]. Several PLD genes have now been identified and it is probable that different isoforms regulate distinct functions. Defining the subcellular localisation of each isoform would facilitate understanding of their roles. Previous PLD localisation studies have been based largely on enzyme activity measurements, which cannot distinguish between isoforms [2,5]. We have cloned the cDNAs encoding human PLD1a and PLD1b from an HL60 cell cDNA library and expressed them as catalytically active fusion proteins with green fluorescent protein (GFP) in COS-1 cells and RBL-2H3 cells, a mast cell model which degranulates upon cross-linking of the high-affinity immunoglobulin E (IgE) receptor. In unstimulated cells, GFP-PLD1b colocalised with secretory granule and lysosomal markers; it was not found at the plasma membrane or nucleus and did not colocalise with markers for the Golgi. Stimulation or RBL-2H3 cells through IgE receptor cross-linking caused plasma membrane recruitment of GFP-PLD1b. Inhibition of IgE-receptor-stimulated, PLD-catalysed phosphatidate formation suppressed secretion of granule and lysosomal contents, but did not affect translocation of GFP-PLD1b. These experiments suggest that PLD1 plays a role in regulated exocytosis rather than endoplasmic reticulum (ER) to Golgi membrane transport.

The sepsis syndrome and the cancer patient: respiratory management and active physiotherapy

Cancer and its treatment place heavy physical and metabolic demands on a patient. Sepsis exacerbates this and may lead to hypoxia. Timely physiotherapy can help improve respiratory function and, together with other members of the multidisciplinary team, in the long-term will help to return the patient to previous levels of function.

Intra-articular injection of ketorolac in the rat knee joint: effect on articular cartilage and synovium

We have investigated the effects of intra-articular (i.a.) administration of ketorolac in the rat knee joint. Thirty Sprague-Dawley rats were given 0.25 ml of a standard preparation of ketorolac trometamol (10 mg ml-1) by injection into the right knee joint and 0.25 ml of 0.9% physiological saline solution by injection into the left knee as a control. Ten rats were killed at 24 h, 10 at 48 h and 10 at 5 days after injection. The joints were prepared and sectioned for histological examination. There was significantly more inflammation in those knees that had received i.a. ketorolac at all times of examination, with the most severe changes occurring 5 days after injection. A further group of 10 rats were given 0.25 ml of 10% w/v ethanol in physiological saline (similar to the vehicle for parenteral ketorolac) injected into the knee joint, with a 0.9% saline control injected in the other knee. These rats were then killed at 5 days (as this was the time interval after which we found the maximum inflammatory response in the earlier phase of our study). The joints were prepared and examined histologically. We feel that the absence of inflammatory changes in these joints make it unlikely that ethanol was responsible for the inflammation produced by ketorolac injection.

RAMPs regulate the transport and ligand specificity of the calcitonin-receptor-like receptor

Calcitonin-gene-related peptide (CGRP) and adrenomedullin are related peptides with distinct pharmacological profiles. Here we show that a receptor with seven transmembrane domains, the calcitonin-receptor-like receptor (CRLR), can function as either a CGRP receptor or an adrenomedullin receptor, depending on which members of a new family of single-transmembrane-domain proteins, which we have called receptor-activity-modifying proteins or RAMPs, are expressed. RAMPs are required to transport CRLR to the plasma membrane. RAMP1 presents the receptor at the cell surface as a mature glycoprotein and a CGRP receptor. RAMP2-transported receptors are core-glycosylated and are adrenomedullin receptors.

Transcriptional activation of the macrophage migration-inhibitory factor gene by the corticotropin-releasing factor is mediated by the cyclic adenosine 3',5'- monophosphate responsive element-binding protein CREB in pituitary cells

Macrophage migration-inhibitory factor (MIF) has recently been identified as a pituitary hormone that functions as a counterregulatory modulator of glucocorticoid action within the immune system. In the anterior pituitary gland, MIF is expressed in TSH- and ACTH-producing cells, and its secretion is induced by CRF. To investigate MIF function and regulation within pituitary cells, we initiated the characterization of the MIF 5'-regulatory region of the gene. The -1033 to +63 bp of the murine MIF promoter was cloned 5' to a luciferase reporter gene and transiently transfected into freshly isolated rat anterior pituitary cells. This construct drove high basal transcriptional activity that was further enhanced after stimulation with CRF or with an activator of adenylate cyclase. These transcriptional effects were associated with a concomitant rise in ACTH secretion in the transfected cells and by an increase in MIF gene expression as assessed by Northern blot analysis. A cAMP-responsive element (CRE) was identified within the MIF promoter region which, once mutated, abolished the cAMP responsiveness of the gene. Using this newly identified CRE, DNA-binding activity was detected by gel retardation assay in nuclear extracts prepared from isolated anterior pituitary cells and AtT-20 corticotrope tumor cells. Supershift experiments using antibodies against the CRE-binding protein CREB, together with competition assays and the use of recombinant CREB, allowed the detection of CREB-binding activity with the identified MIF CRE. These data demonstrate that CREB is the mediator of the CRF-induced MIF gene transcription in pituitary cells through an identified CRE in the proximal region of the MIF promoter.

Neuroendocrine regulation of GnRH and behavior during aging in birds

Avian species exhibit a great variety of life-long patterns in reproduction. Japanese quail are relatively short lived and undergo an age-related loss of reproductive function, making this species an excellent model for the study of the basic biology of aging. Because individuals age at variable rates, sexual behavior has provided a useful index to assess reproductive status of individuals of the same chronological age. Further, exogenous testosterone restores sexual behavior in reproductively senescent male quail, thereby providing evidence for a continued ability of the system to respond. In addition, we have been studying hypothalamic neuroendocrine systems that regulate the endocrine as well as behavioral components of reproduction. Overall, our findings point to the hypothalamic neuroendocrine systems as the site of initial age-related alterations that contribute to the reproductive deterioration. Specifically, we studied adrenergic, opioid peptide, vasotocin, and aromatase systems to understand their relationship to the cGnRH-I system and their potential role in the deterioration of the cGnRH-I system during aging. Our findings provide evidence for qualitative and quantitative alterations in the aromatase enzyme system, which can be partially restored with exogenous testosterone. In addition, other neuronal systems, including the vasotocin system, decline with the loss of gonadal steroids and are restimulated with exogenous testosterone. We will synthesize the data relative to these neuroendocrine systems with attention to the effects of gonadal steroids on these systems during aging.

Contamination in expressed breast milk following breast cleansing

The purpose of this study was to determine if preexpression breast cleansing reduced the bacterial count in expressed breast milk. The study involved the collection of 178 breast milk samples (89 matched samples); 38 matched samples were from mothers of term infants and 51 matched samples were from mothers of preterm infants. One half of the samples were collected following breast cleansing with Phisoderm and tap water. The other half were collected following breast cleansing with tap water only. Hand and equipment washing with Phisoderm and tap water preceded all sample collections. Storage containers were sterile. Samples were cultured for pathogenic and nonpathogenic bacteria and examined at 24 and 48 hours. Data were analyzed by Wilcoxon Matched-Pairs sign test and Chi square. Breast cleansing with Phisoderm and water was not more effective than water alone at reducing nonpathogenic bacteria or eliminating pathogenic bacteria. Mothers of preterm infants had higher levels of both nonpathogenic and pathogenic bacteria than mothers of full-term infants. The most common form of bacterial contamination was coagulase-negative Staphylococcus epidermidis. This particular bacteria is found in higher levels in the stools of breast fed infants than formula fed infants and it also the most common contaminant found in the blood of preterm infants who develop sepsis. The findings of this study reveal that chemical interventions may not be effective at rendering breast milk free from pathogenic bacteria. More research is needed to determine the optimal cleansing protocol to achieve bacterial decontamination of breast milk or to determine the clinically acceptable level of contamination based on the effects on infants.

Patient-maintained propofol sedation. Assessment of a target-controlled infusion system

We have developed a system which allows patients to operate a target-controlled infusion of propofol to provide sedation and we have studied its use in 36 unpremedicated patients undergoing local and regional anaesthetic procedures lasting 10-280 min. An intravenous propofol infusion was started at a target plasma level of 1 microgram.ml-1. The patient was able to increase the target propofol concentration in 0.2- microgram.ml-1 increments by pressing a demand button. There was a lockout interval of 2 min and a maximum permissible target concentration of 3 micrograms.ml-1. There was considerable interindividual variability in propofol consumption (mean 39.3 micrograms.kg-1.min-1, range 3-131 micrograms.kg-1.min-1), no cardiovascular instability and little oversedation. Eight patients required supplementary oxygen. Optimal sedation was provided at median target concentrations of 0.8-0.9 microgram.ml-1. The target-controlled infusion system bias was-47% and the inaccuracy was 48%. Patient satisfaction was high and 89% said that they would definitely use the technique again. This technique combines the benefits of target-controlled infusion with patient-controlled feedback and produces safe intra-operative sedation.

Insulin secretion is regulated by the glucose-dependent production of islet beta cell macrophage migration inhibitory factor

Macrophage migration inhibitory factor (MIF), originally identified as a cytokine secreted by T lymphocytes, was found recently to be both a pituitary hormone and a mediator released by immune cells in response to glucocorticoid stimulation. We report here that the insulin-secreting beta cell of the islets of Langerhans expresses MIF and that its production is regulated by glucose in a time- and concentration-dependent manner. MIF and insulin colocalize by immunocytochemistry within the secretory granules of the pancreatic islet beta cells, and once released, MIF appears to regulate insulin release in an autocrine fashion. In perifusion studies performed with isolated rat islets, immunoneutralization of MIF reduced the first and second phase of the glucose-induced insulin secretion response by 39% and 31%, respectively. Conversely, exogenously added recombinant MIF was found to potentiate insulin release. Constitutive expression of MIF antisense RNA in the insulin-secreting INS-1 cell line inhibited MIF protein synthesis and decreased significantly glucose-induced insulin release. MIF is therefore a glucose-dependent, islet cell product that regulates insulin secretion in a positive manner and may play an important role in carbohydrate metabolism.