Examining the role of dopamine in methylphenidate's effects on resting brain function

The amplitude of low-frequency fluctuations (ALFF) and global functional connectivity density (gFCD) are fMRI (Functional MRI) metrics widely used to assess resting brain function. However, their differential sensitivity to stimulant-induced dopamine (DA) increases, including the rate of DA rise and the relationship between them, have not been investigated. Here we used, simultaneous PET-fMRI to examine the association between dynamic changes in striatal DA and brain activity as assessed by ALFF and gFCD, following placebo, intravenous (IV), or oral methylphenidate (MP) administration, using a within-subject double-blind placebo-controlled design. In putamen, MP significantly reduced D2/3 receptor availability and strongly reduced ALFF and increased gFCD in the brain for IV-MP (Cohen's d > 1.6) but less so for oral-MP (Cohen's d < 0.6). Enhanced gFCD was associated with both the level and the rate of striatal DA increases, whereas decreased ALFF was only associated with the level of DA increases. These findings suggest distinct representations of neurovascular activation with ALFF and gFCD by stimulant-induced DA increases with differential sensitivity to the rate and the level of DA increases. We also observed an inverse association between gFCD and ALFF that was markedly enhanced during IV-MP, which could reflect an increased contribution from MP's vasoactive properties.

Human genetics and molecular genomics of Chiari malformation type 1

Chiari malformation type 1 (CM1) is the most common structural brain disorder involving the craniocervical junction, characterized by caudal displacement of the cerebellar tonsils below the foramen magnum into the spinal canal. Despite the heterogeneity of CM1, its poorly understood patho-etiology has led to a 'one-size-fits-all' surgical approach, with predictably high rates of morbidity and treatment failure. In this review we present multiplex CM1 families, associated Mendelian syndromes, and candidate genes from recent whole exome sequencing (WES) and other genetic studies that suggest a significant genetic contribution from inherited and de novo germline variants impacting transcription regulation, craniovertebral osteogenesis, and embryonic developmental signaling. We suggest that more extensive WES may identify clinically relevant, genetically defined CM1 subtypes distinguished by unique neuroradiographic and neurophysiological endophenotypes.

Mutation of key signaling regulators of cerebrovascular development in vein of Galen malformations

To elucidate the pathogenesis of vein of Galen malformations (VOGMs), the most common and most severe of congenital brain arteriovenous malformations, we performed an integrated analysis of 310 VOGM proband-family exomes and 336,326 human cerebrovasculature single-cell transcriptomes. We found the Ras suppressor p120 RasGAP (RASA1) harbored a genome-wide significant burden of loss-of-function de novo variants (2042.5-fold, p = 4.79 x 10-7). Rare, damaging transmitted variants were enriched in Ephrin receptor-B4 (EPHB4) (17.5-fold, p = 1.22 x 10-5), which cooperates with p120 RasGAP to regulate vascular development. Additional probands had damaging variants in ACVRL1, NOTCH1, ITGB1, and PTPN11. ACVRL1 variants were also identified in a multi-generational VOGM pedigree. Integrative genomic analysis defined developing endothelial cells as a likely spatio-temporal locus of VOGM pathophysiology. Mice expressing a VOGM-specific EPHB4 kinase-domain missense variant (Phe867Leu) exhibited disrupted developmental angiogenesis and impaired hierarchical development of arterial-capillary-venous networks, but only in the presence of a "second-hit" allele. These results illuminate human arterio-venous development and VOGM pathobiology and have implications for patients and their families.

Neural circuit selective for fast but not slow dopamine increases in drug reward

The faster a drug enters the brain, the greater its addictive potential, yet the brain circuits underlying the rate dependency to drug reward remain unresolved. With simultaneous PET-fMRI we linked dynamics of dopamine signaling, brain activity/connectivity, and self-reported 'high' in 20 adults receiving methylphenidate orally (results in slow delivery) and intravenously (results in fast delivery) (trial NCT03326245). We estimated speed of striatal dopamine increases to oral and IV methylphenidate and then tested where brain activity was associated with slow and fast dopamine dynamics (primary endpoint). We then tested whether these brain circuits were temporally associated with individual 'high' ratings to methylphenidate (secondary endpoint). A corticostriatal circuit comprising the dorsal anterior cingulate cortex and insula and their connections with dorsal caudate was activated by fast (but not slow) dopamine increases and paralleled 'high' ratings. These data provide evidence in humans for a link between dACC/insula activation and fast but not slow dopamine increases and document a critical role of the salience network in drug reward.

Silicosis and silicotuberculosis among respiratory hospital admissions: A cross-sectional survey in northern Tanzania

Background

There is little evidence describing respiratory disease among 40.5 million small-scale miners worldwide.

Objectives

To describe the prevalence and clinical characteristics of adult respiratory inpatients with silicosis and silicotuberculosis in a tertiary hospital in Tanzania that serves a small-scale mining region.

Methods

In this retrospective, cross-sectional survey, patient files from admissions between 2010 and 2020 were opportunistically selected and included if a respiratory diagnosis had been made.

Results

Of 223 patients with respiratory conditions, 32 (14.3%; 95% confidence interval (CI) 10.0 - 19.6) were diagnosed with silicosis and 17 (7.6%; 95% CI 4.5 - 11.9) with silicotuberculosis. Mining was the most frequent occupation in those with silicosis (n=15/32; 46.9%) and silicotuberculosis (n=15/17; 88.2%). Of those with silicosis or silicotuberculosis, 26/49 (53.1%) were aged <45 years.

Conclusion

Our study suggests that silicosis and silicotuberculosis are common among male and female respiratory inpatients with occupational exposure. The study highlights the role of occupational exposures in respiratory disease in developing economies.

Study synopsis

What the study adds. This retrospective, cross-sectional survey describes the prevalence of silicosis and silicotuberculosis among adult respiratory inpatients admitted to a tertiary hospital in northern Tanzania. It is the first study to describe the prevalence and characteristics of respiratory inpatients with silicosis and silicotuberculosis in a small-scale mining region of Africa. A high prevalence of silicosis (14.3%) and silicotuberculosis (7.6%) was found. Patients were often aged <45 years, and the majority required oxygen therapy.Implications of the findings. The high prevalence of advanced silicosis and silicotuberculosis in miners presenting at a young age raises concerns about high occupational silica exposures and, importantly, suggests a need for community-based research, which our team is planning to undertake.

Striatal D1 and D2 receptor availability are selectively associated with eye-blink rates after methylphenidate treatment

Eye-blink rate has been proposed as a biomarker of the brain dopamine system, however, findings have not been consistent. This study assessed the relationship between blink rates, measured after oral placebo) (PL) and after a challenge with oral methylphenidate (MP; 60 mg) and striatal D1 receptor (D1R) (measured at baseline) and D2 receptor (D2R) availability (measured after PL and after MP) in healthy participants. PET measures of baseline D1R ([¹¹C]NNC112) (BL-D1R) and D2R availability ([¹¹C]raclopride) after PL (PL-D2R) and after MP (MP-D2R) were quantified in the striatum as non-displaceable binding potential. MP reduced the number of blinks and increased the time participants kept their eyes open. Correlations with dopamine receptors were only significant for the eye blink measures obtained after MP; being positive for BL-D1R in putamen and MP-D2R in caudate (PL-D2R were not significant). MP-induced changes in blink rates (PL minus MP) were negatively correlated with BL-D1R in caudate and putamen. Our findings suggest that eye blink measures obtained while stressing the dopamine system might provide a more sensitive behavioral biomarker of striatal D1R or D2R in healthy volunteers than that obtained at baseline or after placebo.

PET imaging in human participants revealed that D1 and D2 dopamine receptor availability was associated with eye-blink rates following treatment with oral methylphenidate, but not a placebo.

Sex differences in weight gain during medication-based treatment for opioid use disorder: A meta-analysis and retrospective analysis of clinical trial data

BACKGROUND

Side effects of medications for opioid use disorder (MOUD) such as weight gain contribute to their stigma. Substantial evidence suggests that women have a more severe side effect profile to MOUD than men, and concerns about weight gain during treatment are prevalent. However, the few studies reporting sex differences in weight gain during treatment show conflicting results and are restricted to methadone. In addition, little is known about possible sex differences in weight gain to buprenorphine, which is the most commonly prescribed MOUD in the United States.

METHODS

To address these issues, we performed a systematic review and meta-analysis on the few studies reporting longitudinal data on sex differences in body mass index (BMI) gain during methadone treatment (Study 1). In a separate study, we also re-analyzed data from trial CTN-0030 of the National Institute on Drug Abuse Clinical Trial Network (NIDA CTN), which involved a 12-week buprenorphine treatment regimen (Study 2; n = 360; 209 Male, 151 Female).

RESULTS

For Study 1, across all papers reporting longitudinal data (k = 4, n = 362 OUD patients), there were BMI increases that ranged from 2.2 to 5.4 BMI after at least one year of methadone treatment, but there were no significant sex differences in BMI increases (Standardized Mean Difference, Female > Male = 0.352, SE =0.270; 95 % CI = [-0.18 0.88]; p = .193). Study 2 showed no significant differences in weight before and after 12 weeks of buprenorphine treatment nor did it show sex differences in weight change with treatment (β = 2.34, p = .511).

CONCLUSION

These analyses corroborate evidence of weight gain with methadone treatment but did not observe a sex-based disparity in weight gain with methadone or buprenorphine treatment for OUD.

Ketamine use disorder: preclinical, clinical, and neuroimaging evidence to support proposed mechanisms of actions

Ketamine, a noncompetitive NMDA receptor antagonist, has been exclusively used as an anesthetic in medicine and has led to new insights into the pathophysiology of neuropsychiatric disorders. Clinical studies have shown that low subanesthetic doses of ketamine produce antidepressant effects for individuals with depression. However, its use as a treatment for psychiatric disorders has been limited due to its reinforcing effects and high potential for diversion and misuse. Preclinical studies have focused on understanding the molecular mechanisms underlying ketamine's antidepressant effects, but a precise mechanism had yet to be elucidated. Here we review different hypotheses for ketamine's mechanism of action including the direct inhibition and disinhibition of NMDA receptors, AMPAR activation, and heightened activation of monoaminergic systems. The proposed mechanisms are not mutually exclusive, and their combined influence may exert the observed structural and functional neural impairments. Long term use of ketamine induces brain structural, functional impairments, and neurodevelopmental effects in both rodents and humans. Its misuse has increased rapidly in the past 20 years and is one of the most common addictive drugs used in Asia. The proposed mechanisms of action and supporting neuroimaging data allow for the development of tools to identify 'biotypes' of ketamine use disorder (KUD) using machine learning approaches, which could inform intervention and treatment.

Inflammatory Markers in Substance Use and Mood Disorders: A Neuroimaging Perspective

Chronic exposure to addictive drugs in substance use disorders and stressors in mood disorders render the brain more vulnerable to inflammation. Inflammation in the brain, or neuroinflammation, is characterized by gliosis, microglial activation, and sustained release of cytokines, chemokines, and pro-inflammatory factors compromising the permeability of the blood-brain barrier. There is increased curiosity in understanding how substance misuse and/or repeated stress exposure affect inflammation and contribute to abnormal neuronal activity, altered neuroplasticity, and impaired cognitive control, which eventually promote compulsive drug-use behaviors and worsen mood disorders. This review will emphasize human imaging studies to explore the link between brain function and peripheral markers of inflammation in substance use disorders and mood disorders.

Dietary sugar inhibits satiation by decreasing the central processing of sweet taste

From humans to vinegar flies, exposure to diets rich in sugar and fat lowers taste sensation, changes food choices, and promotes feeding. However, how these peripheral alterations influence eating is unknown. Here we used the genetically tractable organism D. melanogaster to define the neural mechanisms through which this occurs. We characterized a population of protocerebral anterior medial dopaminergic neurons (PAM DANs) that innervates the β’2 compartment of the mushroom body and responds to sweet taste. In animals fed a high sugar diet, the response of PAM-β’2 to sweet stimuli was reduced and delayed, and sensitive to the strength of the signal transmission out of the sensory neurons. We found that PAM-β’2 DANs activity controls feeding rate and satiation: closed-loop optogenetic activation of β’2 DANs restored normal eating in animals fed high sucrose. These data argue that diet-dependent alterations in taste weaken satiation by impairing the central processing of sensory signals.

Obesity is a major health problem affecting over 650 million adults worldwide. It is typically caused by overeating high-energy foods, which often contain a lot of sugar. Consuming sugary foods triggers the production of a reward signal called dopamine in the brains of insects and mammals, which reinforces sugar-consuming behavior. The brain balances this with a process called ‘sensory-enhanced satiety’, which makes foods that provide a stronger sensation of sweetness better at reducing hunger and further eating.

High-energy food was scarce for most of human evolution, but over the past century sugar has become readily available in our diet leading to an increase in obesity. Last year, a study in fruit flies reported that a sugary diet reduces the sensitivity to sweet flavors, which leads to overeating and weight gain. It appears that this sensitivity is linked to the effectiveness of sensory-enhanced satiety. However, the mechanism linking diets high in sugar and overeating is still poorly understood. One hypothesis is that fruit flies estimate the energy content of food based on the degree of dopamine released in response to the sugar.

May et al. compared the responses of neurons in fruit flies fed a normal diet to those in flies fed a diet high in sugar. As expected, both groups activated the neurons involved in the dopamine reward response when they tasted sugar. However, when the flies were on a sugar-heavy diet, these neurons were less active. This was because the neurons responsible for tasting sweetness were activated less in flies fed a high-sugar diet, leading to a lowered response by the neurons that produce dopamine. The flies in these experiments were genetically engineered so that the dopamine-producing neurons could be artificially activated in response to light, a technique called optogenetics. When May et al. applied this technique to the flies on a sugar-heavy diet, they were able to stop these flies from overeating.

These findings provide further evidence to support the idea that a sugary diet reduces the brain’s sensitivity to overeating. Given the significant healthcare cost of obesity to society, this improved understanding could help public health initiatives focusing on manufacturing food that is lower in sugar.

Development and applications of computer image analysis algorithms for scoring of PD-L1 immunohistochemistry

Immune checkpoint inhibitors targeting programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) have rapidly become integral to standard-of-care therapy for non-small cell lung cancer and other cancers. Immunohistochemical (IHC) staining of PD-L1 is currently the accepted and approved diagnostic assay for selecting patients for PD-L1/PD-1 axis therapies in certain indications. However, the inherent biological complexity of PD-L1 and the availability of several PD-L1 assays – each with different detection systems, platforms, scoring algorithms and cut-offs – have created challenges to ensure reliable and reproducible results based on subjective visual assessment by pathologists. The increasing adoption of computer technologies into the daily workflow of pathology provides an opportunity to leverage these tools towards improving the clinical value of PD-L1 IHC assays. This review describes several image analysis software programs of computer-aided PD-L1 scoring in the hope of driving further discussion and technological advancement in digital pathology and artificial intelligence approaches, particularly as precision medicine evolves to encompass accurate simultaneous assessment of multiple features of cancer cells and their interactions with the tumor microenvironment.

Activation of peripheral 5-HT receptors attenuates colonic sensitivity to intraluminal distension

Tegaserod is a 5-HT(4) receptor partial agonist approved for the treatment of irritable bowel syndrome in women with constipation and in both men and women with chronic constipation. The efficacy of tegaserod is based on the importance of 5-HT(4) receptors regulating intestinal peristalsis and secretion, and possibly visceral sensory pathways. Our aim was to investigate the effect of tegaserod on colorectal sensitivity using models of normal and exaggerated responsiveness to colorectal distension (CRD). The visceromotor responses (VMR) to CRD at graded pressures (0-60 mmHg) were measured by the number of reflex abdominal contractions. Acute colorectal hypersensitivity was induced by intracolonic infusion of dilute acetic acid. Chronic hypersensitivity was observed in rats following spontaneous resolution of trinitrobenzenesulfonic acid-induced colitis. Rats with normosensitive colons served as controls. Tegaserod (0.1-10 mg kg(-1)) caused dose-dependent reduction of the VMR to CRD in control rats and in those with colonic hypersensitivity. 5-HT(4) antagonists reversed the effects of tegaserod in rats with normosensitive colons, and partially inhibited effects in rats with colonic hypersensitivity. Central administration of tegaserod had no inhibitory effect. These results support the assumption that colonic hypersensitivity could be normalized by tegaserod acting, at least in part, through peripheral 5-HT(4) receptors.

Ultrastructural and morphometric features of nodal and impulse-conducting cardiac myocytes of the bat Pipistrellus pipistrellus

Cells of the impulse-generating and conducting tissues of the insect-eating bat Pipistrellus pipistrellus were studied and evaluated using ultrastructural morphometry. Sinoatrial node cells are smaller than working atrial cells and measure about 6.5 microm in diameter. Their mitochondira and myofibril content constitute 23% and 19% of cytoplasmic volume, respectively. Corresponding values for working atrial cells are 23% and 52%. Atrioventricular node cells are 4.2 microm in diameter and contain abundant glycogen in the cytoplasm. The fractional volume of mitochondria in about 24% while that of myofibrils is 7%. Cells of the bundle of His are larger (6-8 microm diameter) and contain more cellular organelles than do nodal cells. Their mitochondria and myofibril contents are 25% and 25%, respectively. Cells in the proximal part of the right bundle branch are slender with diameters averaging 3.4 microm. Mitochondrial content is 23% while myofibrils occupy 20% of the cytoplasmic volume of these cells. Distally located bundle branch cells measure 7-10 microm in diameter with mitochondria and myofibril volumes of 30% and 33%. Subendocardial cells in the ventricular free wall are large reaching 28 microm in diameter (cf. 14-18 microm in working ventricular cells) and have mitochondira and myofibril volume fractions of 32% and 29%, respectively (35% & 40% for working ventricular cells).

The cytotoxic plant protein, beta-purothionin, forms ion channels in lipid membranes

Thionins are small cysteine-containing, amphipathic plant proteins found in seeds and vegetative tissues of a number of plant genera. Many of them have been shown to be toxic to microorganisms such as fungi, yeast, and bacteria and also to mammalian cells. It has been suggested that thionins are present in seeds to protect them, and the germinating seedling, from attack by phytopathogenic microorganisms, but the mechanism by which they kill cells remains unclear. Using electrophysiological measurements, we have shown that beta-purothionin from wheat flour can form cation-selective ion channels in artificial lipid bilayer membranes and in the plasmalemma of rat hippocampal neurons. We suggest that the generalized toxicity of thionins is due to their ability to generate ion channels in cell membranes, resulting in the dissipation of ion concentration gradients essential for the maintenance of cellular homeostasis.

Cloning and characterization of MS5 from Arabidopsis: a gene critical in male meiosis

In this paper, we describe the cloning of the MS5 gene, a gene essential for male fertility in Arabidopsis. We previously defined the MS5 locus by characterizing an EMS-induced allele, ms5-1. We identified a new allele of MS5 (ms5-2) that was T-DNA-generated and used the T-DNA tag to clone the gene. Sequencing of mutant and wild-type alleles together with complementation of the ms5-1 mutant phenotype with a wild-type genomic clone confirmed the identity of the gene. Differences between the phenotypes of the two mutant alleles could be attributed to differences in mutant gene structure. The semi-dominant and dominant negative phenotypes of the ms5-2 mutant probably result from production of a truncated polypeptide. An unknown locus in Landsberg erecta can counteract the dominant negative phenotype of ms5-2. Mutations in MS5 cause the formation 'polyads'--tetrads with more than four pools of chromosomes after male meiosis. Similarities between the MS5 sequence and that of a number of proteins were found; two that may be significant were with a synaptonemal complex protein and with a regulatory subunit of a cyclin-dependent kinase. The MS5 gene is a member of a small gene family highly conserved amongst plant species.

Ovule and embryo development, apomixis and fertilization

Genetic analyses, particularly in Arabidopsis, have led to the identification of mutants that define different steps of ovule ontogeny, pollen stigma interaction, pollen tube growth, and fertilization. Isolation of the genes defined by these mutations promises to lead to a molecular understanding of these processes. Mutants have also been obtained in which processes that are normally triggered by fertilization, such as endosperm formation and initiation of seed development, occur without fertilization. These mutants may illuminate apomixis, a process of seed development without fertilization extant in many plants.

Optical immunoassay test for group A beta-hemolytic streptococcal pharyngitis. An office-based, multicenter investigation

OBJECTIVE

To compare the accuracy of an optical immunoassay (OIA) for the rapid diagnosis of group A streptococcal pharyngitis with blood agar plate (BAP) culture.

DESIGN

Blinded comparison with criterion standard.

SETTING

A total of 6 private pediatricians' offices, 3 in Connecticut and 3 in Chicago, III.

PATIENTS

A total of 2113 consecutive patients with acute pharyngitis, 983 in Connecticut and 1130 in Chicago.

MAIN OUTCOME MEASURES

The sensitivities and specificities of OIA and BAP culture (both performed and interpreted in the office) were determined using a research laboratory's interpretation of a combination of BAP culture and Todd-Hewitt broth (THB) culture of transport tube pledget as criterion standard.

RESULTS

Among patients in Connecticut, the sensitivities of the OIA and BAP culture were 94% and 89%, respectively (P=.004), while the specificities were 96% and 99%, respectively (P=.001). Among patients in Chicago, the sensitivities of the OIA and BAP culture were 79% and 72%, respectively (P<.001), while the specificities were 89% and 99%, respectively (P<.001). In each of the 6 pediatricians' offices, the OIA was more sensitive than the BAP culture. Combining the data from Connecticut and Chicago, the overall sensitivities of the OIA and BAP culture were 84% and 78%, respectively (P<.001), while the specificities were 93% and 99%, respectively (P<.001).

CONCLUSIONS

The results of this comprehensive office-based investigation suggest that with adequately trained personnel, negative OIA test results may not always need to be routinely confirmed with BAP cultures.

An inservice on wheels

In our hospital nurses were unsure about products to order for ostomy patients. To address nurses' concerns, a group of representatives from the Central Supply Department and Nursing Department as well as the clinical nurse specialist and patient care specialist was formed. The group developed an inservice on wheels entitled, "Send Me One of Everything" which was rotated throughout the hospital. This article describes the setup of the cart, methods used to update skills, and evaluation of the process. The inservice on wheels was an effective way to update the staff and decrease waste.

The diversity of case management needs for the care of homeless persons

Health care providers have been attempting to meet the special needs of homeless people on a national level since 1984. The need to implement strategies specific to serving the diversity of services required by homeless people has been apparent. To devise appropriate strategies, clinical information was drawn from the Health Resources and Services Administration-Health Care for the Homeless (HRSA-HCH) projects, which were created in 1987 primarily to fill such a need. In addition, data gathered by the HCH projects (1984-87) funded by the Robert Wood Johnson and Pew Memorial Trust were used. It is suggested that the past mode of providing health care for the homeless has been found to be inadequate when confronting the complex problems of the homeless person of today. In general, health care providers need to focus more on case management activities, which may include activities not necessarily associated with the provision of health care services (for example, finding and providing food, clothing, shelter, and assessing entitlement eligibility) to achieve the ultimate goal--stabilization--and when possible, reintegration of the homeless person back into society.

Isolation and molecular analysis of the maize P locus

The maize P locus is involved in the synthesis of a red flavonoid pigment in the pericarp, cob and other floral tissues. The tissue-specific pattern of expression of certain P alleles suggests that P may be a complex locus, with more than one functional unit. The P-VV allele, which specifies variegated pericarp and variegated cob, however, shows that insertion and excision of the transposable element Ac affects both pericarp and cob expression as though cob and pericarp pigmentation are controlled by a single gene. Using Ac as a transposon tag, we have isolated 34 kb of genomic DNA from the P-VV and P-RR allele. The cloned DNA contains two 5.8 kb cross-hybridizing regions, in direct orientation relative to each other, separated by 6.6 kb of intervening DNA. A sequence motif of 250 bp is repeated at three locations within the cloned region: once within each of the 5.8 kb repeats, and once outside the 5.8 kb repeats. DNA fragments flanking the Ac element detect five transcripts in RNA from wild type (P-RR) that are absent from mutant (P-VV) tissues. To localize the transcribed sequences, DNA probes spanning the 34 kb of cloned DNA were used in Northern analysis of RNA from mutant and wild-type kernels. The results suggest the presence of a single transcriptional unit located primarily within the DNA between the 5.8 kb repeats. The five RNAs transcribed from this region may be formed by alternative splicing. The size of the P gene derived from the length of the transcribed region seems much smaller than the gene size estimated from Ac-induced P-VV mutations.

Transcription from a plant gene promoter in animal cells

The promoter segment of a plant gene (maize alcohol dehydrogenase 1 (Adh 1)) has been fused to two bacterial reporter genes, Ecogpt (1) and neo (2), in pSV2-derived vectors and introduced into cultured mammalian cells by DNA transfection. The pAdh1-gpt plasmids transformed the recipient cells for resistance to mycophenolic acid plus xanthine (3) and the analogous pAdh1-neo plasmid transformed cells to G418 resistance (2). S1 analysis of transient transfections of CV1 cells with various derivatives of pAdh1-gpt confirmed that production of gpt mRNA is initiated at the Adh1 promoter at and near the same site used in transcription of the intact Adh1 gene in maize. Moreover, expression of the Adh1 promoter was increased 10-20 fold if the SV40 early region enhancer sequence was included in the same molecule.

Swamp rice farming: possible effects on endemicity of schistosomiasis mansoni and haematobia in a population in Liberia

To obtain a better understanding of the possible influence of swamp rice farming on the patterns of Schistosoma mansoni and Schistosoma haematobium infections, the populations of two communities in rural liberia were studied. In one village, Balama (population of 435), swamp rice farms were initiated six years before the survey; in the other nearby community, Gbarta (population of 216), swamp rice farms had not yet been initiated. The prevalence of S. mansoni infection in Balama was 87% vs. 9% in Gbarta (P less than 0.01). The geometric and arithmetic mean egg counts for all infected subjects in Balama were respectively 263 and 671/g feces. in Gbarta, the geometric and arithmetic mean egg counts were 150 and 129/g feces. S. haematobium eggs were detected in 42% of subjects in Balama vs. 11% in Gbarta (P less than 0.01). Hematuria correlated with the presence of S. haematobium eggs in urine. These data indicate that there is a significantly higher prevalence and intensity of schistosomiasis mansoni and haematobia in a community where swamp rice farming has been utilized for 6 years compared to a nearby village where this water irrigation and drainage practice has not yet been implemented.

Studies on the epidemiology of schistosomiasis in Liberia: the prevalence and intensity of schistosomal infections in Bong County and the bionomics of the snail intermediate hosts

Urine samples from 3548 individuals residing in six of the eight districts which comprise Bong County, Liberia, the project area of the Bong County Agricultural Development Project (BCADP), and fecal specimens from 3408 of these individuals were examined for schistosome ova. A total of 164 water sites, including rice paddies, were surveyed for schistosome vector snails and monthly changes in snail population density and infection rate were determined in selected water sites. Bulinus globosus was more widely distributed than Biomphalaria pfeifferi but the latter species showed a higher infection prevalence (12.3%) than the former one (10.3%). Snail population density and infection rate fluctuated with season, being higher in the dry season and lower during periods of heavy rainfall. Dessication and/or heat stress may have contributed to the contraction of snail population size at the end of the dry season. More water sites contained infected snails during December through February than at any other time of the year. In selected water sites examined at monthly intervals, mean snail density was higher in rice paddies than in other water contact sites but the latter showed a higher prevalence of infected snails than the former. The overall prevalence of Schistosoma mansoni (24.8%) was significantly higher than that of S. haematobium (22.7%) but the difference in prevalence rates of two species in school children was not statistically significant. The intensity of S. haematobium infection (13.2 means G) was significantly higher than that of S. mansoni (6.3 means G). Mixed infections in school children did not have a significant effect on egg output. The prevalence and intensity of S. haematobium showed a dramatic decline between the age groups 0-15 and 20-50 + years old; the differences between these age groups in S. mansoni infection were unremarkable. In Zota, Jorquelle and Kokoya Districts, prevalence rates of S. haematobium were higher than those of S. mansoni; the reverse was observed in Suakoko and Panta-Kpai Districts but relative prevalence rates varied according to specific locality in each district. A south to north stratification of schistosomal infection prevalence was observed similar to the west to east gradient reported by Saladin et al. (1980). New rice paddies developed during the three year operational period of the BCADP contained little or no vector snails and schistosomal infections in farm families of these paddies reflected the characteristic of the disease in corresponding localities.(ABSTRACT TRUNCATED AT 400 WORDS)

The impact of schistosomiasis among rural populations in Liberia

Human infection with Schistosoma haematobium and/or Schistosoma mansoni is known to be widespread in central Liberia, but no information is available about its clinical manifestations or its significance for public health. Details of a cross-sectional morbidity study are reported. A sample from hospital out-patients and samples from 3 villages situated in areas with different transmission patterns (lack of transmission, transmission of only S. haematobium and transmission of both S. haematobium and S. mansoni) were examined. All 184 individuals were examined by standardized case history, clinical and parasitological investigations, including a skin snip for onchocerciasis and a count of schistosomal and other intestinal worm eggs from stool and urine. A complete blood count, urine analysis, urine cultures, hepatitis-B surface antigen determination and abdominal X-rays were also carried out. Schistosomal egg counts ranged from 1 to 6200/10 ml urine for S. haematobium and from 1 to 228/g stool for S. mansoni. Difficulties for the definition of accurate morbidity indices are discussed. Except for haematuria and dysuria, the overall morbidity in the study area was not striking, neither for S. haematobium nor for S. mansoni infection. No cumulative pathology was observed in patients with mixed infection. The frequency of hypertension, hepato- and splenomegaly, ascites and bacteriuria was low and no relationship to schistosomiasis could be established. Bladder calcifications were found in 10% of people living in an area of transmission of S. haematobium. Although the intensity of infection is low for both S. haematobium and S. mansoni, long-term follow-up studies are essential for a more accurate assessment of the public health importance of these parasites.

A pilot control trial of schistosomiasis in central Liberia by mass chemotherapy of target populations, combined with focal application of molluscicide

In an area of high transmission of Schistosoma haematobium and S. mansoni in Central Liberia, populations of five villages and intermediate host snails were surveyed for two years. In three of these villages focal application of molluscicide (niclosamide) in the main transmission sites was combined with mass chemotherapy of a target population representing 76 to 90% of the contamination index. In the two other villages, which served as control, the prevalence indexes remained stable or increased a little during the period of this study. A three dose metrifonate mass treatment was applied in one village with only S. haematobium infections. The compliance was very poor for the second and third dose but the quantity of eggs eliminated by the whole population present before and after mass treatment was reduced by 50%. No snails were found after molluscicide applications but as the incidence remained unchanged it is suspected that inhabitants have been reinfected by going to their fields. Concurrent metrifonate and niridazole mass treatment in one dose was applied in another village with only S. haematobium infections. Molluscicide applications reduced the snail population by 80% but did not affect the transmission. Prevalence indexes were almost the same before and after this intervention. In the last village, praziquantel (40 mg/kg in 1 dose) was used because both S. haematobium and S. mansoni infections were present. Molluscicide applications reduced the snail population by 99% and 87% for Bulinus globosus and Biomphalaria pfeifferi, respectively. This intervention stopped the transmission of S. haematobium for at least one year and reduced the prevalence from 21% to 4.6%. On the contrary for S. mansoni infections, the incidence remained very high (50%) and the prevalence was unchanged after one year follow-up. This could be explained by lower efficacy of praziquantel against S. mansoni (cure rate: 53%) and of molluscicide application against B. pfeifferi, which are highly susceptible to S. mansoni (infection rate 44%). The importance of migration in these villages is emphasized. Prevalence indexes were largely influenced by the arrival of newcomers who played a more important role in the maintenance of transmission after target mass chemotherapy than the infected persons excluded from this treatment. The costs per capita protected were 3.33 US $ for metrifonate, 1.53 for metrifonate and niridazole combined and 1.67 US$ for praziquantel. These figures do not include costs for parasitological examinations.(ABSTRACT TRUNCATED AT 400 WORDS)

Clinical observations in 42 patients with Lassa fever

Under continuous observation of several months, 42 patients from the eastern province of Sierra Leone, Liberia (Lofa County), and neighbouring Guinea were identified as Lassa fever cases by indirect immunofluorescent antibody technique, indicating that the disease is endemic in these areas. The clinical course varied from mild disease to severe illness with haemorrhagic disorders. The fatality rate was 14%. The occurrence of only two possible secondary cases suggests that person-to-person spread of the disease is unimportant epidemiologically. There was a wide range of patients' ages, tribes, and occupations, including a 2 months old baby and a white US citizen. Clinical, laboratory, and histopathological investigations demonstrated the panorganotropism of Lassa virus. Haematological tests in few selected haemorrhagic cases with Lassa fever did not support coagulation disorders or thrombocytopenia as causing the bleeding tendency. The histopathologic changes bear resemblance to those observed in Argentinian and Bolivian haemorrhagic fever, both being caused by viruses of the Arena group. However, Lassa virus hepatitis may be differentiated from liver lesions occurring in yellow fever, Marburg virus disease, and Ebola (Maridi) haemorrhagic fever.

Preliminary epidemiological survey of schistosomiasis in central and southern Liberia

Some basic epidemiological data on schistosomiasis in central and southern Liberia were collected. A study of snail density fluctuations was carried out in waterbodies bordering the road between Harbel and Gbarnga. Samples from schoolchildren living in ten selected villages were examined for Schistosoma spp. and other helminths. In the coastal region no snail hosts were found, the prevalence rates in schoolchildren were low and the infections were apparently imported. Inland, the intermediate host of Schistosoma haematobium Bulinus globosus was common and the prevalence of urinary schistosomiasis was high. Further inland, around Gbarnga, both Schistosma mansoni and S. haematobium were endemic. The seasonal patterns of patent cercarial infections in Bulinus globosus and Biomphalaria pfeifferi are described. Both snail densities and cercarial infection rates were markedly reduced by heavy rains. The results of the study may contribute to the planning of future integrated control strategy.

Systematics and chromosomes of New Guinea Rattus

Karyotypes of six endemic New Guinea Rattus species are described. They fall into two distinct types. The R. leucopus group, which is a compact group morphologically, have very similar karyotypes of 32 or 34 chromosomes and are distinct from the Australian Rattus. The karyotypes of the second type, the R. sordidus group, are related to Australian members of the same group. What has previously been regarded as a single species of the sordidus group, R. sordidus gestroi, is shown to consist of two distinct populations with different karyotypes and skull parameters; we consider that they should be regarded as two species.

Donovanosis in Papua New Guinea

Clinical and epidemiological observations on 87 cases of donovanosis seen at Port Moresby General Hospital are presented, with detailed reports of three cases in which the disease was more severe. The circumstances of infection described were consistent with venereal transmission. Chloramphenicol and gentamicin were effective in curing the disease, while streptomycin was found to be ineffective in a number of cases tested. Complement-fixation tests with Donovania antigen revealed the presence of antibodies in all but one of 23 cases tested, and in nine out of fourteen other patients who on clinical grounds were suspected of having donovanosis but were negative by smear test. The complement-fixation test with Klebsiella antigen was found to be highly specific for donovanosis, but less sensitive than the test using Donovania antigen. The intracellular location of Donovania in tissue and the presence of antibodies which are apparently not protective suggest that cell-mediated immunity may be important in defence against Donovania infection.