1
|
Nishimoto L, Ikani P, Achanya J, Idowu A, Olisa AL, Walker CF, Gottlieb A, Akolo C. Expanding Access to Oral Preexposure Prophylaxis for People Who Inject Drugs in Bayelsa and Niger States, Nigeria. Glob Health Sci Pract 2023; 11:GHSP-D-22-00370. [PMID: 36853631 PMCID: PMC9972381 DOI: 10.9745/ghsp-d-22-00370] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 01/17/2023] [Indexed: 02/12/2023]
Abstract
INTRODUCTION While oral preexposure prophylaxis (PrEP) is recommended for all individuals with substantial risk of acquiring HIV, people who inject drugs (PWID) have not been prioritized for oral PrEP services in most settings. The Meeting Targets and Maintaining Epidemic Control (EpiC) project implemented a comprehensive community-based program to increase access to and uptake of oral PrEP services among PWID in Bayelsa and Niger States, Nigeria. PROGRAM DESCRIPTION EpiC established partnerships with community-based organizations working with the PWID community, identified hotspots (common locations for socialization and drug use), and engaged PWID in tailoring oral PrEP services. The HIV prevention package provided in hotspots and drop-in centers included HIV testing, oral PrEP, postexposure prophylaxis, sexually transmitted infection screening and management, condoms and lubricants, PWID-specific risk reduction counseling, and referrals to other support programs. At drop-in centers, paralegal and psychological services were also provided. Peer outreach workers led outreach efforts. All PWID who tested HIV negative were eligible for oral PrEP screening. National oral PrEP eligibility criteria included: no suspicion of acute HIV infection, absence of proteinuria, and willingness to use oral PrEP as prescribed. We used descriptive analysis of routine programmatic data to illustrate program outcomes. RESULTS From January 2020 to September 2021, 13,286 HIV tests were completed for PWID. Of these, 12,111 (91.16%) had negative results. Among those testing negative, 8,190 (67.62%) were screened for oral PrEP eligibility, and 2,661 (32.49%) were eligible. A total of 2,659 PWID (100% [312/312] among eligible females; 99.91% [2,347/2,349] among eligible males) initiated oral PrEP. LESSONS LEARNED Provision of oral PrEP services to PWID in Nigeria is feasible through a peer-led, differentiated, and holistic approach that addresses structural barriers among the PWID community. Greater efforts are needed to understand the needs and barriers to better tailor HIV services to reach females and other subpopulations in this community that are harder to reach.
Collapse
|
2
|
Black R, Fontaine O, Lamberti L, Bhan M, Huicho L, El Arifeen S, Masanja H, Walker CF, Mengestu TK, Pearson L, Young M, Orobaton N, Chu Y, Jackson B, Bateman M, Walker N, Merson M. Drivers of the reduction in childhood diarrhea mortality 1980-2015 and interventions to eliminate preventable diarrhea deaths by 2030. J Glob Health 2019; 9:020801. [PMID: 31673345 PMCID: PMC6815873 DOI: 10.7189/jogh.09.020801] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND Childhood diarrhea deaths have declined more than 80% from 1980 to 2015, in spite of an increase in the number of children in low- and middle-income countries (LMIC). Possible drivers of this remarkable accomplishment can guide the further reduction of the half million annual child deaths from diarrhea that still occur. METHODS We used the Lives Saved Tool, which models effects on mortality due to changes in coverage of preventive or therapeutic interventions or risk factors, for 50 LMIC to determine the proximal drivers of the diarrhea mortality reduction. RESULTS Diarrhea treatment (oral rehydration solution [ORS], zinc, antibiotics for dysentery and management of persistent diarrhea) and use of rotavirus vaccine accounted for 49.7% of the diarrhea mortality reduction from 1980 to 2015. Improvements in nutrition (stunting, wasting, breastfeeding practices, vitamin A) accounted for 38.8% and improvements in water, sanitation and handwashing for 11.5%. The contribution of ORS was greater from 1980 to 2000 (58.0% of the reduction) than from 2000 to 2015 (30.7%); coverage of ORS increased from zero in 1980 to 29.5% in 2000 and more slowly to 44.1% by 2015. To eliminate the remaining childhood diarrhea deaths globally, all these interventions will be needed. Scaling up diarrhea treatment and rotavirus vaccine, to 90% coverage could reduce global child diarrhea mortality by 74.1% from 2015 levels by 2030. Adding improved nutrition could increase that to 89.1%. Finally, adding increased use of improved water sources, sanitation and handwashing could result in a 92.8% reduction from the 2015 level. CONCLUSIONS Employing the interventions that have resulted in such a large reduction in diarrhea mortality in the last 35 years can virtually eliminate remaining childhood diarrhea deaths by 2030.
Collapse
Affiliation(s)
- Robert Black
- Johns Hopkins University, Bloomberg School of Public Health, Department of International Health, Institute for International Programs, Baltimore, Maryland, USA
| | - Olivier Fontaine
- World Health Organization, Department of Maternal, Newborn, Child and Adolescent Health Child and Adolescent Health and Development, Geneva, Switzerland
| | - Laura Lamberti
- Bill & Melinda Gates Foundation, Enteric Diarrheal Diseases, Seattle, Washington, USA
| | - Maharaj Bhan
- Indian Institute of Technology, New Delhi, India
| | - Luis Huicho
- Centro de Investigación en Salud Materna e Infantil, Centro de Investigación para el Desarrollo Integral y Sostenible and School of Medicine, Lima, Peru
| | - Shams El Arifeen
- International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh
| | | | - Christa Fischer Walker
- US Centers for Disease Control and Prevention, Maternal and Child Health, Windhoek, Namibia
| | | | - Luwei Pearson
- United Nations Children's Fund (UNICEF), New York, New York, USA
| | - Mark Young
- United Nations Children's Fund (UNICEF), New York, New York, USA
| | - Nosa Orobaton
- Bill & Melinda Gates Foundation, Maternal, Newborn and Child Health, Seattle, Washington, USA
| | - Yue Chu
- Johns Hopkins University, Bloomberg School of Public Health, Department of International Health, Institute for International Programs, Baltimore, Maryland, USA
| | - Bianca Jackson
- Johns Hopkins University, Bloomberg School of Public Health, Department of International Health, Institute for International Programs, Baltimore, Maryland, USA
| | - Massee Bateman
- US Agency for International Development (USAID), Jakarta, Indonesia
| | - Neff Walker
- Johns Hopkins University, Bloomberg School of Public Health, Department of International Health, Institute for International Programs, Baltimore, Maryland, USA (deceased)
| | - Michael Merson
- Duke University, Duke Global Health Institute, Durham, North Carolina, USA
| |
Collapse
|
3
|
Black RE, Walker CF. Do Water, Sanitation, and Hygiene Interventions Prevent Childhood Diarrhea? J Infect Dis 2019; 221:1241-1243. [DOI: 10.1093/infdis/jiz183] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Accepted: 04/26/2019] [Indexed: 11/14/2022] Open
Affiliation(s)
- Robert E Black
- Institute for International Programs, Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
| | - Christa Fischer Walker
- Institute for International Programs, Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
| |
Collapse
|
4
|
Abstract
Zinc deficiency has been estimated to result in more than 450,000 child deaths annually by increasing the risk of diarrhea and pneumonia mortality. Trials of daily supplemental zinc have shown preventive benefits in childhood diarrhea with a 20% reduction in incidence. Use of zinc in treatment of diarrhea has also been successful in shortening the duration of the episode by 10% and reducing the number of prolonged episodes. The World Health Organization recommends that zinc supplements be used for 10-14 days for every episode of childhood diarrhea along with oral hydration and feeding. Large-scale effectiveness trials of these recommendations in Bangladesh and India have found a reduction in hospitalizations due to diarrhea and pneumonia and in child mortality. Trials have also demonstrated a reduction in the incidence childhood pneumonia with zinc supplements and some, but not all, studies have found a therapeutic benefit of zinc as adjunctive treatment along with antibiotics as well. Preventive zinc also improves the growth of children in developing countries and reduces total deaths in 1-to 4-year-old children by 18%. Zinc supplementation is an intervention with proven effectiveness and broad application to address pneumonia and diarrhea, the two most important childhood infectious diseases globally.
Collapse
Affiliation(s)
- Robert E Black
- Department of International Health, Johns Hopkins University, Bloomberg School of Public Health, Baltimore, MD, USA
| | | |
Collapse
|
5
|
Black RE, Cousens S, Johnson HL, Lawn JE, Rudan I, Bassani DG, Jha P, Campbell H, Walker CF, Cibulskis R, Eisele T, Liu L, Mathers C. Global, regional, and national causes of child mortality in 2008: a systematic analysis. Lancet 2010; 375:1969-87. [PMID: 20466419 DOI: 10.1016/s0140-6736(10)60549-1] [Citation(s) in RCA: 1831] [Impact Index Per Article: 130.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
BACKGROUND Up-to-date information on the causes of child deaths is crucial to guide global efforts to improve child survival. We report new estimates for 2008 of the major causes of death in children younger than 5 years. METHODS We used multicause proportionate mortality models to estimate deaths in neonates aged 0-27 days and children aged 1-59 months, and selected single-cause disease models and analysis of vital registration data when available to estimate causes of child deaths. New data from China and India permitted national data to be used for these countries instead of predictions based on global statistical models, as was done previously. We estimated proportional causes of death for 193 countries, and by application of these proportions to the country-specific mortality rates in children younger than 5 years and birth rates, the numbers of deaths by cause were calculated for countries, regions, and the world. FINDINGS Of the estimated 8.795 million deaths in children younger than 5 years worldwide in 2008, infectious diseases caused 68% (5.970 million), with the largest percentages due to pneumonia (18%, 1.575 million, uncertainty range [UR] 1.046 million-1.874 million), diarrhoea (15%, 1.336 million, 0.822 million-2.004 million), and malaria (8%, 0.732 million, 0.601 million-0.851 million). 41% (3.575 million) of deaths occurred in neonates, and the most important single causes were preterm birth complications (12%, 1.033 million, UR 0.717 million-1.216 million), birth asphyxia (9%, 0.814 million, 0.563 million-0.997 million), sepsis (6%, 0.521 million, 0.356 million-0.735 million), and pneumonia (4%, 0.386 million, 0.264 million-0.545 million). 49% (4.294 million) of child deaths occurred in five countries: India, Nigeria, Democratic Republic of the Congo, Pakistan, and China. INTERPRETATION These country-specific estimates of the major causes of child deaths should help to focus national programmes and donor assistance. Achievement of Millennium Development Goal 4, to reduce child mortality by two-thirds, is only possible if the high numbers of deaths are addressed by maternal, newborn, and child health interventions. FUNDING WHO, UNICEF, and Bill & Melinda Gates Foundation.
Collapse
Affiliation(s)
- Robert E Black
- Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
6
|
Rimoin AW, Hamza HS, Vince A, Kumar R, Walker CF, Chitale RA, da Cunha ALA, Qazi S, Steinhoff MC. Evaluation of the WHO clinical decision rule for streptococcal pharyngitis. Arch Dis Child 2005; 90:1066-70. [PMID: 15941772 PMCID: PMC1720142 DOI: 10.1136/adc.2004.069120] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIMS To prospectively assess the WHO clinical decision rule (CDR) for group A beta haemolytic streptococcal (GABHS) pharyngitis in three countries. METHODS A prospective, observational cohort study in urban outpatient clinics in Rio de Janeiro, Cairo, and Zagreb. There were 2225 children aged 2-12 years with cough, rhinorrhoea, red or sore throat; 1810 of these with sore throat were included in the analysis. RESULTS The proportion of children presenting with sore throat and found to have GABHS pharyngitis ranged from 24.6% (Brazil) to 42.0% (Croatia). WHO CDR sensitivity was low for all sites in both age groups. In children age 5 or older, sensitivity ranged from 3.8% in Egypt to 10.8% in Brazil. In children under 5, sensitivity was low (0.0-4.6%) Specificity was high in both age groups in all countries (93.8-97.4%). CONCLUSIONS In these populations, the current WHO CDR has high specificity, but low sensitivity; it did not detect up to 96.0% of children who have laboratory confirmed GABHS pharyngitis. A CDR with higher sensitivity should be developed for use in regions where rheumatic fever and rheumatic heart disease are still major health problems.
Collapse
Affiliation(s)
- A W Rimoin
- Department of Epidemiology, School of Public Health, University of California, Los Angeles, CA, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Fischer Walker C, Kordas K, Stoltzfus RJ, Black RE. Interactive effects of iron and zinc on biochemical and functional outcomes in supplementation trials. Am J Clin Nutr 2005; 82:5-12. [PMID: 16002793 DOI: 10.1093/ajcn.82.1.5] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Iron and zinc are essential micronutrients for human health. Deficiencies in these 2 nutrients remain a global problem, especially among women and children in developing countries. Supplementation with iron and zinc as single micronutrients enhances distinct and unique biochemical and functional outcomes. These micronutrients have the potential to interact when given together; thus, it is important to assess the biochemical and functional evidence from clinical trials before supplementation policies are established. We reviewed randomized trials that assessed the effects of iron and zinc supplementation on iron and zinc status. On the basis of this review, zinc supplementation alone does not appear to have a clinically important negative effect on iron status. However, when zinc is given with iron, iron indicators do not improve as greatly as when iron is given alone. In most of the studies, iron supplementation did not affect the biochemical status of zinc, but the data are not clear regarding morbidity outcomes. Although some trials have shown that joint iron and zinc supplementation has less of an effect on biochemical or functional outcomes than does supplementation with either mineral alone, there is no strong evidence to discourage joint supplementation. Supplementation programs that provide iron and zinc together are an efficient way to provide both micronutrients, provided the benefits of individual supplementation are not lost. Further research is needed before health policies on joint supplementation programs can be established.
Collapse
Affiliation(s)
- Christa Fischer Walker
- Bloomberg School of Public Health, Department of International Health, Johns Hopkins University, Baltimore, MD 21205, USA
| | | | | | | |
Collapse
|
8
|
Abstract
BACKGROUND Most of the world's children live in regions where laboratory facilities are not available. In these regions, clinical prediction rules can be useful to guide clinicians' decisions on antibiotic therapy for streptococcal pharyngitis, and to reduce routine presumptive antibiotic therapy for all pharyngitis. METHODS Prospective cohort study to assess diagnostic signs and develop a prediction rule. Bivariate and multivariate analyses were used to develop clinical rules. Participants were 410 children in Cairo, Egypt, aged from 2 to 12 y, presenting with complaint of sore throat and whose parents provided consent. Main outcome measures included presence of signs and symptoms, and positive group A beta hemolytic streptococcal (GABHS) culture. RESULTS 101 (24.6%) children had positive GABHS culture. Pharyngeal exudate, tender or enlarged anterior cervical lymph nodes, season, absence of rash, or cough or rhinitis were associated with positive culture in bivariate and multivariate analyses. Three variables (enlarged nodes, no rash, no rhinitis), when used in a cumulative score, showed 92% sensitivity and 38% specificity in these children. CONCLUSIONS The proposed three-variable clinical prediction rule for GABHS may be useful when diagnostic laboratories are not available. In this setting, the rule identified more than 90% of true cases. Compared to universal treatment of all pharyngitis, the rule will reduce antibiotic use in GABHS-negative cases by about 40%.
Collapse
Affiliation(s)
- Mark C Steinhoff
- Department of International Health, Bloomberg School of Public Health, Department of Pediatrics, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA.
| | | | | | | |
Collapse
|
9
|
Abstract
Zinc is an essential micronutrient for human growth, development, and immune function. Zinc deficiency impairs overall immune function and resistance to infection. Mild to moderate zinc deficiency can be best detected through a positive response to supplementation trials. Zinc supplementation has been shown to have a positive effect on the incidence of diarrhea (18% reduction, 95% CI: 7-28%) and pneumonia (41% reduction, 95% CI: 17-59%), and might lead to a decrease in the incidence of malaria. Zinc has also proven to decrease the duration of diarrhea by 15% (95% CI: 5-24%). Maternal zinc supplementation may lead to a decrease in infant infections. Studies assessing the role of zinc supplementation among persons with HIV, tuberculosis, and the common cold have not been conclusive. Two studies have shown zinc supplementation to decrease child mortality by more than 50%. Zinc clearly has an important role in infant and childhood infectious diseases; programs to increase the intake of zinc among deficient populations are needed.
Collapse
Affiliation(s)
- Christa Fischer Walker
- Department of International Health, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland 21205, USA.
| | | |
Collapse
|
10
|
Sikka SC, Wang R, Kukuy E, Walker CF, Hellstrom WJ. The detrimental effects of electric current on normal human sperm. J Androl 1994; 15:145-50. [PMID: 8056638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
This in vitro study was conducted to determine the direct effects of electric current and associated increase in temperature on human sperm. Washed sperm samples from normal volunteers were subjected to an electric current (0 to 100 mA) in a small, customized Plexiglas chamber for up to 10 minutes. Resistive heating was monitored by a miniature temperature probe. An aliquot (7 microliters) obtained from the exposed sample (at 0, 3, 7, and 10 minute intervals) was evaluated for sperm motion parameters, viability, gross morphology, and electron microscopic analyses. As the current increased, there was a time-dependent decrease in the percentages of motility, viability, and curvilinear velocity. Light and electron microscopic evaluations of the sperm showed no demonstrable damage to the head, mid piece, or tail regions on electric stimulation. A gradual time-dependent increase in the temperature of the medium was observed with electric current. Separate evaluations in the absence of an electric current showed a significant increase in percent motility and curvilinear velocity until 40 degrees C. These results suggest that an electric current, independent of temperature (up to 40 degrees C), is detrimental to sperm motion and viability. Further studies are indicated to evaluate whether electric current during electroejaculation may be in part responsible for poor sperm recovery in men with spinal cord injury.
Collapse
Affiliation(s)
- S C Sikka
- Department of Urology, Tulane University, New Orleans, Louisiana
| | | | | | | | | |
Collapse
|
11
|
Waring AJ, Housworth CM, Voorhies RM, Douglas JR, Walker CF, Connolly SE. A prototype retractor system designed to minimize ischemic brain retractor injury: initial observations. Surg Neurol 1990; 34:139-43. [PMID: 2385819 DOI: 10.1016/0090-3019(90)90062-t] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The authors have developed and patented a neurosurgical retractor system incorporating an infrared emitter and detector that allows detection of cerebral pulsations. Gentle contact with the surface of cat brains shows cerebral pulsations that correlate with arterial pulse as well as mechanical ventilation. The amplitude of cerebral pulsations decreases with higher retraction pressure and disappears at approximately 20 mmHg. The pressure on the surface of the brain decreased 50% in 5 minutes even though the position of the retractor was maintained constant. The authors postulate that monitoring cerebral pulsation may prove useful in clinical neurosurgery with respect to avoiding excessive retraction, which causes brain damage.
Collapse
Affiliation(s)
- A J Waring
- Department of Anesthesiology, Ochsner Clinic, New Orleans, Louisiana 70121
| | | | | | | | | | | |
Collapse
|
12
|
Heath RG, Walker CF. Correlation of deep and surface electroencephalograms with psychosis and hallucinations in schizophrenics: a report of two cases. Biol Psychiatry 1985; 20:669-74. [PMID: 3995113 DOI: 10.1016/0006-3223(85)90102-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
|
13
|
Seto YJ, Majeau-Chargois D, Lymangrover JR, Dunlap WP, Walker CF, Hsieh ST. Investigation of fertility and in utero effects in rats chronically exposed to a high-intensity 60-Hz electric field. IEEE Trans Biomed Eng 1984; 31:693-702. [PMID: 6500589 DOI: 10.1109/tbme.1984.325392] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
|
14
|
Heath RG, Fitzjarrell AT, Walker CF. Kappa opiate receptor agonists: effects on behavior and on brain function and structure in rhesus monkeys. Biol Psychiatry 1984; 19:1045-74. [PMID: 6089918] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
In the present study several drugs that are predominantly agonists of kappa receptors were tested in rhesus monkeys prepared with deep and surface brain electrodes. The administration of two benzomorphan derivatives and of ethylketocyclazocine induced acute behavioral effects resembling catatonia concomitant with generalized spike and slow-wave electroencephalographic activity at widespread brain sites, that lasted for about 1 hr. After administration of one to three doses of these agonists (the benzomorphan derivatives to five monkeys and the ethylketocyclazocine to two monkeys), chronic recording changes developed, characterized by continuous high-amplitude spiking activity focal at the anterior septal region and periaqueductal gray of the mesencephalon. They increased in intensity with the passage of time, the monkeys having been followed as long as 5 months without further drug administration. Light microscopy and electron microscopy showed no structural abnormalities in the monkey brains at the sites of altered recordings, although occasional dendritic atrophy was noted at all cortical and subcortical brain sites examined. Chronic recording changes did not develop in a monkey that received U-50,488H on eight occasions. And none of the electrode-implanted monkeys that served as controls (having received no kappa agonists) developed recording changes. The sites affected by the active kappa agonists were those at which abnormal activity has been correlated with psychotic behavior. The ability of the kappa agonists to induce a lasting physiologic change without corresponding structural change at those focal sites implicated in schizophrenia may prove a useful probe in further investigations into the cause of schizophrenia and its ultimate treatment.
Collapse
|
15
|
Abstract
A technique for numerical solution to complex electric field distribution problems has been devised. The specific application for which it was developed is the analysis of current density and isopotential line spacing from implanted neurostimulation electrodes. Three configurations of cerebellar stimulation electrodes in clinical use were studied for current spread to regions distant from the cerebellum using a planar model of the human head, neck, and upper torso in mid-saggital section. It was found that an array of cathodes on the superior cerebellar surface and an array of anodes on the inferior cerebellar surface causes significant current spread to the brainstem, a prediction confirmed by clinical observation in patients with previously implanted electrodes of this configuration. Results modelling other electrode configurations are also presented, along with a study of the effects of possible inaccuracies in available impedance data for neural tissue.
Collapse
|
16
|
Heath RG, Franklin DE, Walker CF, Keating JW. Cerebellar vermal atrophy in psychiatric patients. Biol Psychiatry 1982; 17:569-83. [PMID: 7093393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Our findings indicate that a notable number of patients who have functional psychosis (50%) or seizures (38%) show cerebellar vermal atrophy on visual inspection of CAT head scans, in contrast to 0.5% to 3.7% of patients with other disorders. In addition to the visual reading of 1700 scans in the present study, we used two methods to demonstrate cerebellar vermal atrophy objectively: (i) low-density measurements of the posterior fossa in relationship to total brain area, and (ii) sagittal reconstruction of the vermis. We postulate that cerebellar vermal atrophy reduces the cerebellum's inhibitory influences on activity of the rostral forebrain structures where unit overactivity has been correlated with emotional dyscontrol and clinical seizures. We further postulate that cerebellar vermal atrophy reduces facilitory activity of the brain's pleasure system (septal region).
Collapse
|
17
|
Heath RG, Rouchell AM, Llewellyn RC, Walker CF. Cerebellar pacemaker patients: an update. Biol Psychiatry 1981; 16:953-62. [PMID: 7306618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Of the initial group of 38 patients in whom we have used cerebellar stimulation for treatment of intractable behavioral pathology, 25 continue to have beneficial effects. However, there have been significant technical problems due to failure of the equipment. While impairing treatment, these complications have provided inadvertent controls. The procedure must still be considered developmental at this time, despite promising therapeutic efficacy.
Collapse
|
18
|
Mullen JB, Walker CF, Nashold BS. An electrophysiological approach to neural augmentation implantation for the control of pain. J Bioeng 1978; 2:65-7. [PMID: 681322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
19
|
Walker CF, Lockhead GR, Markle DR, McElhaney JH. Parameters of stimulation and perception in an artificial sensory feedback system. J Bioeng 1977; 1:251-6. [PMID: 615883] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The relationships between stimulus parameters and perceptions in a prosthetic feedback system were measured using psychophysical methods. Electrical stimulation of the median nerve produced a monotonic relation between frequency of stimulation and the perceived magnitude of the stimulus. There were two qualitatively different perceptions of the stimulation; one for low frequencies and one for high. These two qualities fit different psychophysical continuua, kind of stimulation, and amount of stimulation.
Collapse
|
20
|
|