Vaporized nicotine use among patients in HIV care who smoke tobacco: perceived health effects and effectiveness as a smoking cessation tool

Evidence suggests adverse health effects from vaporized nicotine (VN) use, such as electronic "e" cigarettes, and limited efficacy to aid tobacco cessation. People with HIV (PWH) smoke tobacco at higher rates than the general population, with greater morbidity, highlighting the necessity of effective tobacco cessation tools. PWH may be more vulnerable to adverse effects of VN. Using semi-structured 1:1 interviews, we examined health beliefs regarding VN, patterns of use, and perceived effectiveness for tobacco cessation among PWH in HIV care at three geographically diverse U.S. sites. PWH (n = 24) had limited understanding of VN product content or health effects, presuming VN less harmful than tobacco cigarettes (TC). VN failed to adequately replicate the psychoactive effects or desired ritual of smoking TC. Concurrent TC use, and continuous VN use throughout the day, was common. Satiety using VN was elusive, and consumption quantity was difficult to track. VN had limited desirability and durability as a TC cessation tool among the interviewed PWH.

Telehealth Adoption Across Neurosurgical Subspecialties at a Single Academic Institution During the COVID-19 Pandemic

Objective

The COVID-19 pandemic has dramatically changed health care, forcing providers to adopt and implement telehealth technology to provide continuous care for their patients. Amid this rapid transition from in-person to remote visits, differences in telehealth utilization have arisen among neurosurgical subspecialties. In this study, we analyze the impact of telehealth on neurosurgical healthcare delivery during the COVID-19 pandemic at our institution and highlight differences in telehealth utilization across different neurosurgical subspecialties.

Methods

To quantify differences in telehealth utilization, we analyzed all outpatient neurosurgery visits at a single academic institution. Internal surveys were administered to neurosurgeons and to patients to determine both physician and patient satisfaction with telehealth visits. Patient Likelihood-to-Recommend Press-Ganey scores were also evaluated.

Results

There was a decrease in outpatient visits during the COVID-19 pandemic in all neurosurgical subspecialties. Telehealth adoption was higher in spine, tumor, and interventional pain than in functional, peripheral nerve, or vascular neurosurgery. Neurosurgeons agreed that telehealth was an efficient (92%) and effective (85%) methodology; however, they noted it was more difficult to evaluate and bond with patients. The majority of patients were satisfied with their video visits and would recommend video visits over in-person visits.

Conclusions

During the COVID-19 pandemic, neurosurgical subspecialties varied in adoption of telehealth, which may be due to the specific nature of each subspecialty and their necessity to perform in-person evaluations. Telehealth visits will likely continue after the pandemic as they can improve clinical efficiency; overall, both patients and physicians are satisfied with health care delivery over video.

Impact and correlates of sub-optimal social support among patients in HIV care

Social support (SS) predicts health outcomes among patients living with HIV. We administered a brief, validated measure of SS, the Multifactoral Assessment of Perceived Social Support, within a patient-reported outcomes assessment of health domains in HIV care at 4 U.S. clinics in English and Spanish (n = 708). In univariate analysis, low SS was associated with poorer engagement in care, antiretroviral adherence, and health-related quality of life; current methamphetamine/crystal use, depression, anxiety, and HIV stigma (all p < 0.001); any use of either methamphetamines/crystal, illicit opioids, or cocaine/crack (p = 0.001), current marijuana use (p = 0.012), nicotine use (p = 0.005), and concern for sexually transmitted infection exposure (p = 0.001). High SS was associated with undetectable viral load (p = 0.031). Multivariate analyses found low SS independently associated with depression (risk ratio (RR) 3.72, 95% CI 2.93-4.72), lower adherence (RR 0.76, 95% CI 0.64-0.89), poor engagement in care (RR 2.05, 95% CI 1.44-2.96), and having more symptoms (RR 2.29, 95% CI 1.92-2.75). Medium SS was independently associated with depression (RR 2.59, 95% CI 2.00-3.36), poor engagement in care (RR 1.62, 95% CI 1.15-2.29) and having more symptoms (RR 1.75, 95% CI 1.44-2.13). SS assessment may help identify patients at risk for these outcomes.

Development and content validation of measures assessing adherence barriers and behaviors for use in clinical care

BACKGROUND

Providers are often unaware of poor adherence to prescribed medications for their patients with chronic diseases.

OBJECTIVE

To develop brief, computer-administered patient-reported measures in English and Spanish assessing adherence behaviors and barriers. Design, Participants, and Main Measures: Item pools were constructed from existing measures of medication adherence behaviors and barriers, which informed development of a patient concept elicitation interview guide to identify medication adherence behavior and barrier-related concepts. Two hundred six patients either living with HIV (PLWH) or without were interviewed. Interviews were coded, concepts matched to item pool content, and new items were developed for novel concepts. A provider/investigator team highlighted clinically relevant items. Cognitive interviews were conducted with patients on final candidate items (n = 37). The instruments were administered to 2081 PLWH.

KEY RESULTS

Behavioral themes from concept elicitation interviews included routines incorporating time of day, placement, visual cues, and intentionality to miss or skip doses. Barrier themes included health-related (e.g. depressed mood, feeling ill), attitudes/beliefs (e.g., need for medication), access (e.g., cost/insurance problems), and circumstantial barriers (e.g., lack of privacy, disruption of daily routine). The final instruments included 6 behavior items, and 1 barrier item with up to 23 response options. PLWH endorsed a mean (SD) of 3.5 (1.1) behaviors. The 201 PLWH who missed ≥2 doses in the previous week endorsed a mean (SD) of 3.1 (2.5) barriers. The intraclass correlation coefficient (ICC) for the numbers of behaviors endorsed in 61 PLWH after 4-16 days was 0.54 and for the number of barriers for the 20 PLWH with ≥2 missed doses the ICC was 0.89, representing fair and excellent test-retest reliability.

CONCLUSION

Measures of medication adherence behaviors and barriers were developed for use with patients living with chronic diseases focusing on clinical relevance, brevity, and content validity for use in clinical care.

A new quinoline-based chemical probe inhibits the autophagy-related cysteine protease ATG4B

The cysteine protease ATG4B is a key component of the autophagy machinery, acting to proteolytically prime and recycle its substrate MAP1LC3B. The roles of ATG4B in cancer and other diseases appear to be context dependent but are still not well understood. To help further explore ATG4B functions and potential therapeutic applications, we employed a chemical biology approach to identify ATG4B inhibitors. Here, we describe the discovery of 4-28, a styrylquinoline identified by a combined computational modeling, in silico screening, high content cell-based screening and biochemical assay approach. A structure-activity relationship study led to the development of a more stable and potent compound LV-320. We demonstrated that LV-320 inhibits ATG4B enzymatic activity, blocks autophagic flux in cells, and is stable, non-toxic and active in vivo. These findings suggest that LV-320 will serve as a relevant chemical tool to study the various roles of ATG4B in cancer and other contexts.

Medication understanding among patients living with multiple chronic conditions: Implications for patient-reported measures of adherence

BACKGROUND

Low health literacy is associated with poor medication adherence and poor health outcomes. Limited understanding of prescribed medications may decrease validity of patient-reported adherence measures.

OBJECTIVES

To assess knowledge of names and purposes of prescribed medications among patients with multiple chronic conditions.

METHODS

Individual interviews were conducted with a convenience sample of patients from six U.S. primary care clinics. Participants (n = 57) were English and/or Spanish-speaking patients prescribed 3+ medications for chronic conditions, for which non-adherence may lead to disability or death. In individual interviews, patients were asked to name their medications, explain the purpose of each, and to explain how they distinguish them from one another. Interviews were audio recorded, transcribed, and coded; coded content was quantified by 1) whether or not the patient could name medications; 2) method of categorizing medications; 3) whether or not the purpose of the medication was understood. Descriptive statistics were compiled using Fisher's exact test to determine the relationship between patient knowledge and medication characteristics.

RESULTS

Thirty percent of patients could not name at least one of their medications; 19% did not know their purpose; 30% held misconceptions about the purpose of one or more medications. There was no significant difference in ability to name medications or state their medication's purpose between patients using medi-sets, pre-packaged rolls, or blister packs, and patients who stored pills in their original containers (p = 0.56 and p = 0.73, respectively), or across demographic groups (p = 0.085 to 0.767).

CONCLUSIONS

Many patients demonstrated difficulty identifying the name and purpose of prescribed medications; this did not differ by demographic group or medication storage type. Patients may benefit from routine review of medications with their provider in order to improve health literacy, outcomes, and patient-reported adherence measurement.

The impact of clinical protocols in the management of severe sepsis: a prospective cohort study

This study aimed to assess the availability of clinical protocols and their effect on compliance to the Surviving Sepsis Campaign bundles and on mortality in severe sepsis in ten Singaporean adult teaching intensive care units (ICU). The presence of 11 protocols in the ICUs, steps taken based on the Johns Hopkins University Quality and Safety Research Group's model to translate protocols into practice, and organisational characteristics were assessed. Clinical and research personnel recorded characteristics of patients with severe sepsis who were admitted in July 2009, the achievement of sepsis bundle targets and outcomes. Hospital mortality was 39% for 128 patients. Fewer than half of the ICUs had protocols for early goal-directed therapy, blood cultures, antibiotics, steroids, lung-protective ventilation and weaning. Compliance rates with the resuscitation and management bundles were 18 and 3% respectively. Units with protocols were generally not more likely to achieve associated bundle targets. Steps from the Johns Hopkins model to measure performance, engage teams and sustain and extend interventions were taken in fewer than half of the available protocols. However, on logistic regression analysis, the number of protocols available per ICU was independently and inversely associated with mortality. In conclusion, clinical protocols are infrequently available in Singapore's ICUs and when present do not generally improve compliance to the sepsis bundles. These protocols may, however, be a surrogate marker of the quality of care as they are independently associated with decreased mortality. The use of an integrated and multifaceted approach to translate protocols into practice should be considered.

Severe hyperphosphataemia and associated electrolyte and metabolic derangement following the administration of sodium phosphate for bowel preparation

Sodium phosphate is widely used as an effective bowel preparation agent. It is used in smaller volumes, leading to improved patient tolerance. Although it is generally safe, cases of severe hyperphosphataemia following sodium phosphate administration have been reported in the literature. The common risk factors identified are advanced age, impaired renal function, impaired colonic motility and multiple doses. However, many doctors remain unaware of the dangers associated with this agent. We report six cases of severe electrolyte and metabolic derangement due to sodium phosphate bowel preparation: two patients had delayed awakening from general anaesthesia, and four patients suffered life-threatening consequences.

Antioxidant effects of herbal therapies used by patients with inflammatory bowel disease: an in vitro study

BACKGROUND

Herbal remedies used by patients for treatment of inflammatory bowel disease include slippery elm, fenugreek, devil's claw, Mexican yam, tormentil and wei tong ning, a traditional Chinese medicine. Reactive oxygen metabolites produced by inflamed colonic mucosa may be pathogenic. Aminosalicylates (5-ASA) are antioxidant and other such agents could be therapeutic.

AIMS

To assess the antioxidant effects of herbal remedies in cell-free oxidant-generating systems and inflamed human colorectal biopsies.

METHODS

Luminol-enhanced chemiluminescence in a xanthine/xanthine oxidase cell-free system was used to detect superoxide scavenging by herbs and 5-ASA, and fluorimetry to define peroxyl radical scavenging using a phycoerythrin degradation assay. Chemiluminescence was used to detect herbal effects on generation of oxygen radicals by mucosal biopsies from patients with active ulcerative colitis.

RESULTS

Like 5-ASA, all herbs, except fenugreek, scavenged superoxide dose-dependently. All materials tested scavenged peroxyl dose-dependently. Oxygen radical release from biopsies was reduced after incubation in all herbs except Mexican yam, and by 5-ASA.

CONCLUSIONS

All six herbal remedies have antioxidant effects. Fenugreek is not a superoxide scavenger, while Mexican yam did not inhibit radical generation by inflamed biopsies. Slippery elm, fenugreek, devil's claw, tormentil and wei tong ning merit formal evaluation as novel therapies in inflammatory bowel disease.

Neonatal neurological testing in resource-poor settings

The aim of the study was to design and test a neurological examination for newborns that could be performed reliably by paramedical staff in resource-poor settings. The examination was adapted from a method established by Dubowitz et al., the latest version of which includes an optimality score. The final items in the test were chosen because they were culturally acceptable, could be elicited according to strict but easily comprehensible instructions and because the expected responses could be scored by the descriptions given or by diagrams in the proforma. The shortened examination was easily taught to paramedical staff who achieved a high degree of inter-observer reliability. This shortened version of the examination was piloted by comparing newborns from a Karen refugee camp on the western border of Thailand and from a large maternity hospital in Bangkok with a standardized cohort of newborns in London. The modified shortened version of the test was sufficiently sensitive to identify a number of differences between the cohorts, notably the poor vision performance and markedly reduced tone of the Karen newborns. In conclusion, the test can be used very reliably by paramedical staff and is a useful, simple and portable tool for the neurological assessment of newborn babies where resources are limited.

The use of magnesium sulphate in the intensive care management of an Asian patient with tetanus

Tetanus, a potentially fatal but largely preventable disease through immunisation, is rare in Singapore. Timely diagnosis and appropriate intensive care management is essential to ensure survival. We aim to report the management of such a patient with magnesium sulphate. This has not been reported locally. By maintaining serum magnesium at 3 to 4 mmol/l we were able to control sympathetic overactivity by day 6, stop neuromuscular blockade by day 7 and wean off ventilator by day 11. Aminoglycoside-induced hypomagnesemia was also demonstrated, necessitating an increase in magnesium sulphate infusion rate to maintain serum magnesium at therapeutic level.

Role of neutrophils and alpha1-antitrypsin in coal- and silica-induced connective tissue breakdown

Mineral dusts produce emphysema, and administration of dust to rats results in the rapid appearance of desmosine and hydroxyproline in lavage fluid, confirming that dusts directly induce connective tissue breakdown. To examine the role of neutrophils and alpha1-antitrypsin (alpha1-AT) in this process, we instilled silica or coal into normal rats or rats that had been pretreated with antiserum against neutrophils. One day after dust exposure, lavage fluid neutrophils and desmosine and hydroxyproline levels were all elevated; treatment with antiserum against neutrophils reduced neutrophils by 75%, desmosine by 40-50%, and hydroxyproline by 25%. By 7 days, lavage fluid neutrophils and desmosine level had decreased, whereas macrophages and hydroxyproline level had increased. By ELISA analysis, lavage fluid alpha1-AT levels were increased four- to eightfold at both times. On Western blot, some of the alpha1-AT appeared as degraded fragments, and by HPLC analysis, 5-10% of the methionine residues were oxidized. At both times, lavage fluid exhibited considerably elevated serine elastase inhibitory capacity and also showed elevations in metalloelastase activity. We conclude that, in this model, connective tissue breakdown is initially driven largely by neutrophil-derived proteases and that markedly elevated levels of functional alpha1-AT do not prevent breakdown, thus providing in vivo support for the concept of quantum proteolysis proposed by Liou and Campbell (T. G. Liou and E. J. Campbell. Biochemistry 34: 16171-16177, 1995). Macrophage-derived proteases may be of increasing importance over time, especially in coal-treated animals.

Infection in central lines: antiseptic-impregnated vs standard non-impregnated catheters

We report a survey of 196 consecutive central venous catheters (CVCs) placed in 151 patients in the Intensive Care Unit (ICU) over a ten-month period. Over this time the use of a new antiseptic-impregnated triple lumen CVC (Arrowgard Blue, Arrow International Inc., Pennsylvania, U.S.A.) was alternated on a bimonthly basis with the standard triple-lumen CVC (Arrow International Inc., Pennsylvania, U.S.A.). The overall rate of CVC tip infection was lower in the impregnated CVC group (15.6% vs 30.9%, P < 0.05). The impregnated CVC group had a much lower cumulative infection rate when the dwell time in patients was five days or less (3.3% vs 26.9%, P < 0.05). However, the difference between the cumulative infection rate was not statistically significant (P > 0.05) for dwell times of 6, 7 or 8 days respectively. There was no difference in the CVC related bacteraemia rates between the two groups (3.9% vs 3.7%, P > 0.05).

The origin recognition complex, SIR1, and the S phase requirement for silencing

Silencing of transcription in Saccharomyces cerevisiae has several links to DNA replication, including a role for the origin recognition complex (ORC), the DNA replication initiator, in both processes. In addition, the establishment of silencing at the HML and HMR loci requires cells to pass through the S phase of the cell cycle. Passage through S phase was required for silencing of HMR even under conditions in which ORC itself was no longer required. The requirement for ORC in silencing of HMR could be bypassed by tethering the Sir1 protein to the HMR-E silencer. However, ORC had a Sir1-independent role in transcriptional silencing at telomeres. Thus, the role of ORC in silencing was separable from its role in initiation, and the role of S phase in silencing was independent of replication initiation at the silencers.

Perioperative transfusion strategies: a national survey among anaesthetists

A current concern in perioperative transfusion therapy is the balance between maintaining adequate haemoglobin level and yet avoiding unnecessary homologous blood transfusion. Strategies to minimise the perioperative use of homologous blood include redefining the traditional transfusion trigger of "10/30 rule", and the use of autologous transfusion therapy. Current recommendations for transfusion triggers advocate determining the "minimum acceptable haemoglobin level" for patients according to various other physiological or surgical factors. The current status of practice amongst anaesthetists in the above mentioned transfusion strategies was assessed using a national survey. An overall response rate of 59.4% was obtained. Results showed wide variation among respondents in their criteria used for preoperative and intraoperative transfusion. Recommendations on perioperative transfusion triggers made by various authors were also summarised. Autologous transfusion therapy was also not frequently practised-the reasons for this were identified. We concluded that in order to continually improve on the anaesthetic community's quality of perioperative care, continued education on the subject must be carried out. Certain practical issues also need to be addressed to facilitate the use of perioperative autologous transfusion therapy.

Methylphenidate and attentional training. Comparative effects on behavior and neurocognitive performance in twin girls with attention-deficit/hyperactivity disorder

The effectiveness of four doses (5-mg, 10-mg, 15-mg, 20-mg) of methylphenidate (MPH) and attentional training (AT) were evaluated using neurocognitive instruments (Continuous Performance Test; Matching Unfamiliar Figures Test), narrow- and broad-band rating scales in the context of a double-blind, placebo-control, within-subject reversal design for dizygotic twin girls with Attention-Deficit/Hyperactivity Disorder (ADHD). Both interventions proved effective for improving neurocognitive test performance and behavior, although broad-band ratings revealed dose-response curves different from those obtained from the neurocognitive tests. Implications for clinical management of girls with ADHD are discussed.

Silencing and heritable domains of gene expression

Silencing is a process that assembles particular regions of eukaryotic chromosomes into transcriptionally inactive chromatin structures. Silencing involves specialized regulatory sites known as silencers and a combination of general DNA-binding proteins and proteins dedicated to silencing. In the yeast Saccharomyces cerevisiae, these proteins include transcription factors and the origin recognition complex (ORC). Silencing has three recognizably separate phases: establishment, maintenance, and inheritance. At least some silencers are origins of replication, and the establishment of the silenced state requires an S phase-specific event. Once established, the silenced state is heritable, even in the absence of proteins required for its establishment. The silencing of mating-type genes bears many similarities to telomere position effects, and the two processes require many of the same proteins.

Roles of ABF1, NPL3, and YCL54 in silencing in Saccharomyces cerevisiae

A sensitized genetic screen was carried out to identify essential genes involved in silencing in Saccharomyces cerevisiae. This screen identified temperature-sensitive alleles of ORC2 and ORC5, as described elsewhere, and ABF1, NPL3, and YCL54, as described here. Alleles of ABF1 that caused silencing defects provided the genetic proof of Abflp's role in silencing. The roles of Npl3p and Ycl54p are less clear. These proteins did not act exclusively through any one of the three protein binding sites of the HMR-E silencer. Unlike the orc2, orc5, and abf1 mutations that were isolated in the same (or a similar) screen for silencing mutants, neither temperature-sensitive mutation in NPL3 or YCL54 caused overt replication defects.

The origin recognition complex in silencing, cell cycle progression, and DNA replication

This report describes the isolation of ORC5, the gene encoding the fifth largest subunit of the origin recognition complex, and the properties of mutants with a defective allele of ORC5. The orc5-1 mutation caused temperature-sensitive growth and, at the restrictive temperature, caused cell cycle arrest. At the permissive temperature, the orc5-1 mutation caused an elevated plasmid loss rate that could be suppressed by additional tandem origins of DNA replication. The sequence of ORC5 revealed a potential ATP binding site, making Orc5p a candidate for a subunit that mediates the ATP-dependent binding of ORC to origins. Genetic interactions among orc2-1 and orc5-1 and other cell cycle genes provided further evidence for a role for the origin recognition complex (ORC) in DNA replication. The silencing defect caused by orc5-1 strengthened previous connections between ORC and silencing, and combined with the phenotypes caused by orc2 mutations, suggested that the complex itself functions in both processes.

The origin recognition complex has essential functions in transcriptional silencing and chromosomal replication

The role of the origin recognition complex (ORC) was investigated in replication initiation and in silencing. Temperature-sensitive mutations in ORC genes caused defects in replication initiation at chromosomal origins of replication, as measured by two-dimensional (2-D) origin-mapping gels, fork migration analysis, and plasmid replication studies. These data were consistent with ORC functioning as a eukaryotic replication initiator. Some origins displayed greater replication initiation deficiencies in orc mutants than did others, revealing functional differences between origins. Alleles of ORC5 were isolated that were defective for silencing but not replication, indicating that ORC's role in silencing could be separated from its role in replication. In temperature-sensitive orc mutants arrested in mitosis, temperature-shift experiments caused a loss of silencing, indicating both that ORC had functions outside of the S phase of the cell cycle and that ORC was required for the maintenance of the silenced state.

Silencers and domains of generalized repression

Gene expression can be affected by the chromosomal position of the gene. An example of this position effect is silencing of the HML and HMR mating-type loci of Saccharomyces cerevisiae. An in vitro assay revealed that silencing induced a transcription-independent general occlusion of the DNA at HMR from sequence-specific interactions of proteins with DNA. The minimum boundaries of the silenced chromatin structure were determined, as were the contributions of the E and I silencers to the size of the silenced domain. Examination of endonuclease-sensitive sites provided evidence that neither the integrity of the chromosomal duplex nor covalent linkage of the silencers to HMR was important for maintenance of the silenced structure in vitro.

Regulation of Saccharomyces cerevisiae CDC7 function during the cell cycle

The yeast Cdc7 function is required for the G1/S transition and is dependent on passage through START, a point controlled by the Cdc28/cdc2/p34 protein kinase. CDC7 encodes a protein kinase activity, and we now show that this kinase activity varies in the cell cycle but that protein levels appear to remain constant. We present several lines of evidence that periodic activation of CDC7 kinase is at least in part through phosphorylation. First, the kinase activity of the Cdc7 protein is destroyed by dephosphorylation of the protein in vitro with phosphatase. Second, Cdc7 protein is hypophosphorylated and inactive as a kinase in extracts of cells arrested at START but becomes active and maximally phosphorylated subsequent to passage through START. The phosphorylation pattern of Cdc7 protein is complex. Phosphopeptide mapping reveals four phosphopeptides in Cdc7 prepared from asynchronous yeast cells. Both autophosphorylation and phosphorylation in trans appear to contribute to this pattern. Autophosphorylation is shown to occur by using a thermolabile Cdc7 protein. A protein in yeast extracts can phosphorylate and activate Cdc7 protein made in Escherichia coli, and phosphorylation is thermolabile in cdc28 mutant extracts. Cdc7 protein carrying a serine to alanine change in the consensus recognition site for Cdc28 kinase shows an altered phosphopeptide map, suggesting that this site is important in determining the overall Cdc7 phosphorylation pattern.

Coordinate inactivation of class III genes during the Gastrula-Neurula Transition in Xenopus

We have identified a period during early Xenopus development when several different genes transcribed by RNA polymerase III (class III genes) are coordinately inactivated. During the late gastrula stage a major reduction in the number of active transcription complexes gives rise to a pattern of class III gene activity typical of adult somatic cells. This event is referred to as the Gastrula-Neurula Transition and involves the inactivation of genes encoding oocyte-type tRNAs and 5S RNA, along with several heterogeneous RNAs expressed during the blastula and gastrula stages of embryogenesis.

Evaluation of human exposure to the heptachlor epoxide contamination of milk in Hawaii

The commercial milk supply on Oahu was contaminated by heptachlor epoxide for as long as 15 months during 1981-82 at levels possibly as high as 1.2 ug/g, fat basis. Following the contamination, several investigators attempted to evaluate potential adverse health outcomes, especially among infants and young children. However, results of the initial investigations are inconclusive due to lack of reliable measures of heptachlor exposure, use of non-random sampling techniques, and lack of definitive health outcomes attributable to heptachlor epoxide. The design of a current study to assess the body concentrations of heptachlor epoxide and related pesticides in Hawaii is presented. The study is designed (1) to relate these concentrations to prior exposure via the milk contamination, and (2) to assess the reliability of breast milk and serum pesticide concentrations as objective biological markers of body burden. No attempt is made to relate these data to health outcomes; instead, the findings may provide the foundation for future health studies or surveillance of environmental exposure to pesticides in Hawaii.

Dipstick chemical urinalysis: an accurate cost-effective screening test

In a double-blind prospective study of 200 sequential urine specimens the sediment count of leukocytes in the centrifuged urine (white blood cells per high power field) was compared to a chamber count of leukocytes in uncentrifuged urine (white blood cells per microliter.). There was good correlation (coefficient of correlation 0.783, sensitivity 91.9 per cent, specificity 97.6 per cent and efficiency 96.6 per cent) between the more precise chamber count and the more commonly performed sediment count if the methodology of the sediment count was standardized. In a double-blind prospective study the results of the sediment count for leukocytes and erythrocytes were compared to the leukocyte esterase and hemoglobin dipstick results of urine specimens from 1,346 adults who underwent multiphasic screening. The dipsticks were found to be sensitive to physiologic limits for leukocytes and erythrocytes, with only 0.9 per cent false negative results for each. Formed elements in the urine not detectable by dipstick, such as casts and crystals, were present in 3 per cent of the specimens. Among patients who had significant pyuria, hematuria or formed elements not detectable by dipstick chemical urinalysis, no significant pathological condition was detected upon retrospective review. Because the chemical dipstick is not quantitative and because the sensitivity of the dipsticks resulted in many false positive findings compared to the sediment count (red and white blood cells 16.4 and 13.2 per cent, respectively) a protocol is offered in which results of screening urine specimens that are positive on dipstick culture would be confirmed by a properly performed microscopic urinalysis. This protocol as applied to an adult screening population would be an accurate, cost-effective method of urine testing.

Pancreatic polypeptide causes diarrhea and weight loss in obese mice but not in lean littermates

Pancreatic polypeptide was infused into obese-hyperglycemic (ob/ob) mice and lean littermates to determine its effect on weight gain. Obese mice continuously infused with 30, 60, or 100 micrograms/day for 7 days developed both diarrhea and weight loss in a dose dependent fashion. Lean littermates infused with 100 micrograms/day developed neither diarrhea nor weight loss. Light microscopic study of ileum and colon revealed no abnormalities. These studies indicate that the effects of pancreatic polypeptide are in part genetically determined since the obese and non-obese mice differ at only one gene locus.

Aldose reductase inhibition: studies with alrestatin

Studies with the aldose reductase inhibitor alrestatin in animal models have suggested that the sorbitol pathway may be of etiologic significance in the pathogenesis of peripheral neuropathy in diabetes. In normal subjects and in highly selected diabetic patients with severe peripheral neuropathy, alrestatin given either intravenously (50 mg/kg body weight) or orally (1 gm q.i.d.) produced no acute toxicity. The serum half-life of alrestatin was approximately 1 hr, and 99% was recovered in the urine within 24 hr. Two diabetic patients receiving alrestatin intravenously reported subjective improvements in clinical symptoms 2 days following the start of infusions. These improvements lasted approximately 3 wk after infusions were discontinued. However, there were no significant objective changes in peripheral nerve condition velocities, or on neurologic examination. In a 30-day oral trial with alrestatin in 4 diabetics, there were no subjective improvements in clinical symptoms nor were there objective improvements on neurologic examination or in peripheral nerve conduction velocities. In this study, peak serum levels of alrestatin were approximately 3 times lower than those obtained on intravenous administration, and it is possible that a high peak serum level is critical to the attainment of adequate tissue drug concentrations. Furthermore, the patients were suffering from severe clinical peripheral neuropathy, which could represent a stage of permanent irreversible nerve damage. Studies with alrestatin in newly diagnosed diabetics with peripheral nerve conduction velocity deficits but without clinical neuropathy might provide a better test of the sorbitol pathway hypothesis.

Somatostatin and pancreatic polypeptide secretion: effects of glucagon, insulin, and arginine

The isolated perfused canine pancreas with duodenal exclusion was used to examine islet hormone output in response to arginine and exogenous glucagon and insulin. Exogenous glucagon (100 ng/ml) stimulated insulin and somatostatin secretion, which occurred in a biphasic pattern. The insulin response to glucagon was markedly enhanced by increased perfusate glucose, unlike the somatostatin response, which was little affected. The insulin and somatostatin responses were seen between 15 and 45 s after the glucagon stimulus. Pancreatic polypeptide secretion was uninfluenced by exogenous glucagon. Biphasic release of glucagon, somatostatin, and pancreatic polypeptide was evoked by 10 mM arginine, the responses first being apparent within less than 30 s. Exogenous insulin (50 mU/ml) infused for 10 min had no statistically significant effect on glucagon, somatostatin, or pancreatic polypeptide secretion. This study suggests that these four islet hormones may all be involved in the dynamic mechanisms of nutrient metabolism. In addition, potential intra-islet paracrine effects are identified.

Hypoglycemia of infancy and nesidioblastosis. Studies with somatostatin

We treated a two-month-old infant with servere intractable hypoglycemia and nesidioblastosis with continuous glucose infusions (0.75 g per kilogram per hour) via a central venous catheter. Preprandial glucose levels on this regimen were 37+/-2 mg per deciliter (+/-S.E.M.). Basal serum insulin levels were within normal fasting levels for this age group but inappropriately elevated for the blood glucose levels. The beta cells were exquisitely sensitive to infusions of synthetic cyclic somatostatin, with a dose-dependent rise in blood glucose and concomitant suppression of serum insulin levels. There was only minimal suppression of plasma glucagon levels. Single subcutaneous injections of 50 microng of protamine zinc somatostatin raised preprandial blood glucose levels to 83+/-3 mg per deciliter for four to five days although preprandial hormone levels were unchanged. These findings indicate that hypoglycemia of infancy is a hyperinsulin state with abnormal basal regulation of insulin secretion.

Ultrastructural localization of pancreatic polypeptide in human pancreas

Human pancreatic polypeptide (HPP) was localized in surgically obtained human pancreas by immunocytochemical electron microscopy. HPP was localized to the secretory granules of cells distinct from the alpha, beta, or delta cells of endocrine islets. The PP cells in 10 patients surveyed were most frequently located in the periphery of the islets. Immunolocalization distinguishes a fifth endocrine cell type in human islets which distinct ultrastructurally by its smaller granule diameter and lack of PP immunoreactivity.

The rate of reaction between cytochrome C peroxidase and hydrogen peroxide is not diffusion limited

The apparent biomolecular rate constant for the cytochrome C peroxidase (EC 1.11.1.5)-hydrogen peroxide reaction has been measured as a function of temperature between 5 and 25 degree C at pH 4,5.5, and 7 and as a function of viscosity over a fifteen-fold range. From the independence of the rate constant on the viscosity, it is concluded that the reaction is not diffusion limited.

A kinetic study of the reaction between cytochrome c peroxidase and hydrogen peroxide. Dependence on pH and ionic strength

The rate of the reaction between cytochrome c peroxidase and hydrogen peroxide was investigated using the stopped-flow technique. The apparent bimolecular rate constant was determined between pH 3.3 and pH 11 as a function of ionic strength. The pH dependence of the apparent bimolecular rate constant can be explained by assuming that two ionizable groups on the enzyme strongly influence the rate of the reaction. At 0.1 M ionic strength, a group with a pKa of 5.5 must be unprotonated and a group with a pKa of 9.8 must be protonated for the enzyme to react rapidly with hydrogen peroxide. The apparent acid dissociation constants depend upon the ionic strength. The true bimolecular rate constant has a value of (4.5 +/- 0.3) X 10(7) M-1 sec-1 and is independent of ionic strength.