Nilesh B. Patel

Role of grooming in reducing tick load in wild baboons (Papio cynocephalus)

Nonhuman primate species spend a conspicuous amount of time grooming during social interactions, a behavior that probably serves both social and health-related functions. While the social implications of grooming have been relatively well studied, less attention has been paid to the health benefits, especially the removal of ectoparasites, which may act as vectors in disease transmission. In this study, we examined the relationship between grooming behavior, tick load (number of ticks), and haemoprotozoan infection status in a population of wild free-ranging baboons (Papio cynocephalus). We found that the amount of grooming received was influenced by an individuals age, sex and dominance rank. The amount of grooming received, in turn, affected the tick load of an individual. Baboons with higher tick loads had lower packed red cell volume (PCV or haematocrit), one general measure of health status. We detected a tick-borne haemoprotozoan, Babesia microti, but its low prevalence in the population precluded identifying sources of variance in infection.

A comparative study to screen dementia and APOE genotypes in an ageing East African population

Previous studies have established cross-cultural methods to screen for ageing- related dementia and susceptibility genes, in particular Alzheimers disease (AD) among the Canadian Cree, African Americans and Yoruba in Nigeria. We determined whether the Community Screening Interview for Dementia (CSID), translated into Kikuyu, a major language of Kenya, could be used to evaluate dementia of the Alzheimer type. Using two sets of coefficients of cognitive and informant scores, two discriminant function (DF) scores were calculated for each of 100 elderly (>65 years) Nyeri Kenyans. When the cut-off points were selected for 100% sensitivities, the specificities of the DF scores were remarkably similar (93.75%) in the Kenyan sample. We propose the adapted CSID can be utilised to detect dementia among East Africans. We also show that apolipoprotein E epsilon 4 allele frequencies were high (approximately 30%) and not different between normal subjects and those with probable AD. There was no evidence to suggest years of education or vascular factors were associated with dementia status.

Evaluation of Risk Factors for Alzheimer’s Disease in Elderly East Africans

A number of biological risk factors have been implicated for Alzheimers disease (AD). The investigation of prevalence rates of AD in crosscultural populations has much potential in validating these factors. We previously assessed brain amyloid beta (A beta) protein deposition and other lesions associated with AD as possible markers for preclinical AD in elderly nondemented East Africans. In further analysis, we demonstrate that 17-19% of elderly East African subjects without clinical neurological disease exhibited neocortical A beta deposits and minimal neurofibrillary changes at necropsy that was qualitatively and quantitatively similar to that in an age-matched elderly control sample from Cleveland, OH. A beta deposits varied from numerous diffuse to highly localized neuritic plaques and were predominantly reactive for the longer A beta 42 species. In parallel studies, we evaluated another recently implicated factor in AD, the apolipoprotein E genotype. We found relatively high frequencies of the apolipoprotein E-epsilon 4 allele in elderly nondemented East Africans. The frequencies were comparable to those in other African populations but higher than in subjects from developed countries. Our limited study suggests that elderly East Africans acquire cerebral lesions found in AD subjects but the apolipoprotein E-epsilon 4 allele may not be a highly specific factor for the disease among East Africans.

Neglected Tropical Diseases and Conditions of the Nervous System

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Khat (Catha edulis) lowers plasma luteinizing hormone (LH) and testosterone secretion, but increases cortisol levels in male rabbits

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“Natural Amphetamine” Khat: A Cultural Tradition or a Drug of Abuse?

AIM This study investigated the effects of fresh khat extract on specific circulating hormones in male rabbits. MATERIALS AND METHODS A total of 25 male New Zealand White rabbits were divided into five groups each comprising five animals. The first four groups were fed four doses (1.5 g/kg, 4.5 g/kg, 13.5 g/kg and 40.5 g/kg body weight) of khat extract twice a week for 5 weeks while the last group, serving as control, was fed only normal saline via intragastric tube. Blood samples were collected at 15 min interval for up to 3 h after khat extract administration and plasma assayed for luteinizing hormone (LH), testosterone and cortisol levels using radioimmunoassay technique. RESULTS Khat extract at all doses significantly lowered (P<0.05) LH pulse frequency, area under LH curve, mean plasma LH and mean plasma testosterone levels. Plasma cortisol levels were significantly elevated (P<0.05) in khat-treated rabbits in a dose-dependent manner. CONCLUSION This study demonstrates that khat may impair reproductive function in male rabbits by interfering with sex hormone profiles.

“Natural Amphetamine” Khat

Khat, Catha edulis Forsk, is among the most widely used plant-based psychoactive substance in the world. Grown in Eastern Africa, Horn of Africa, and southwestern part of the Arabian Peninsula, its fresh young leaves and twigs are used daily by over 20 million people for the psychostimulatory effects it produces in the user, a practice deeply rooted in the history, tradition, and culture of the indigenous population. Once hardly known outside the regions where it is grown and used, khat use has now spread to other countries. This review will cover the, phytochemistry, pharmacokinetics of the active ingredients-cathinone, cathine, norephedrine, neurochemistry, effects on cognitive and executive functions as well as its ability to produce dependency in the user. Whether it is an innocuous cultural practice or a drug of abuse is debatable as the preclinical and clinical data needed to arrive at an authoritative conclusion is lacking.

Proconvulsant effect of khat (Catha edulis) in Sprague dawley rats

Khat, Catha edulis Forsk, is among the most widely used plant-based psychoactive substance in the world. Grown in Eastern Africa, Horn of Africa, and southwestern part of the Arabian Peninsula, its fresh young leaves and twigs are used daily by over 20 million people for the psychostimulatory effects it produces in the user, a practice deeply rooted in the history, tradition, and culture of the indigenous population. Once hardly known outside the regions where it is grown and used, khat use has now spread to other countries. This review will cover the, phytochemistry, pharmacokinetics of the active ingredients-cathinone, cathine, norephedrine, neurochemistry, effects on cognitive and executive functions as well as its ability to produce dependency in the user. Whether it is an innocuous cultural practice or a drug of abuse is debatable as the preclinical and clinical data needed to arrive at an authoritative conclusion is lacking.

Neurobiology of Khat ( Catha edulis Forsk)

ETHNOPHARMACOLOGICAL RELEVANCE Catha edulis (khat) is a plant whose fresh young leaves are used by an estimated five million people in eastern Africa and the Arabian Peninsula as a drug of recreation. The fresh leaves and shoots are rich in cathinone, a psychostimulant with effects similar to those of amphetamines. Psychostimulants produce a dose-related excitation of the central nervous system which can lead to seizures and convulsions. However there are no reports on studies of the effect of this herb on brain excitability and seizures. This knowledge is useful for doctors who may prescribe drugs whose side effects include lowering seizure threshold because there could be additive proconvulsant effect among khat users. AIM OF THE STUDY to determined whether khat lowers pentylenetetrazole (PTZ) seizure threshold. METHODOLOGY Male Sprague dawley rats were given fresh aqueous khat extract, old aqueous khat extract (3 g/kg bw), methylphenidate or saline and the timed intravenous (PTZ) seizure threshold test was used to study its effect on seizure threshold. RESULTS Fresh khat (3 g/kg) and methylphenidate (4 mg/kg) lowered PTZ seizure threshold. CONCLUSION Khat lowers seizure threshold.

Naked mole-rats: behavioural phenotyping and comparison with C57BL/6 mice.

Around 20 million individuals in eastern Africa and the Arabian Peninsula chew the fresh leaves and twigs of Catha edulis Forsk (khat) for its pyschostimulatory effect, a practice deeply rooted in their traditions and cultures. In 1975, the main active ingredient of khat, cathinone, was identified, and found to be structurally related to and with effects similar to amphetamines and other psychostimulants. Animal studies on the neurobiology of khat are sparse and sporadic, being a neglected area of research in the field of drugs of abuse, and most work has focused on the action of cathinone rather than on khat extracts. Like other psychostimulants, the target of khat and cathinone action on the central nervous system is the dopaminergic system involving the nucleus accumbens. Studies on peripheral tissue also show it effects on the serotoninergic system. In animal self-administration studies, cathinone exhibits an addictive and abuse potential and produces psychomotor sensitization. However, there is little information from either human or animal studies on the short- and long-term effect on brain function of daily or frequent khat use with different patterns of consumption; nor is there information on pre-natal and adolescent exposure to khat or its neurotoxic potential. More research on the effects of khat use is needed as it contains a cocktail of alkaloids which is consumed by the user.