Memory deficits associated with khat (Catha edulis) use in rodents.

Khat products and chewing practices are common in East Africa, Middle East for centuries with concomitant socio-economic and public health repercussions. We assessed memory deficits associated with khat use in rodents. Young male CBA mice, 5-7 weeks old (n = 20), weighing 25-35 g were used. Mice were treated with either 40, 120 or 360 mg/kg body weight (bw) methanolic khat extract, or 0.5 ml saline for 10 days. Spatial acquisition, reversal and reference memory were assessed using modified Morris Water maze (MMWM). Mice treated with 40 mg/kg khat extract had longer (t4 = 4.12 p = 0.015) and t4 = 2.28 p = 0.065) escape latency on first and second day during reversal relative to the baseline. Under 120 mg/kg khat dose, the escape latency was shorter (t4 = -2.49 p = 0.05) vs (t3 = -2.5 p = 0.05) on third and fourth day. Further, treatment with 360 mg/kg khat extract resulted in significantly longer time (49.13, 33.5, 40.2 and 35.75) vs. (23.5 s), compared to baseline. Mice treated with khat or control preferred the target quadrant post acquisition while differential pattern was seen during reversal phase. Mice treated with 40 or 120 mg/kg khat showed significant preference for target quadrant. Substantial time (19.9) was spent in the old target compared to the new (16.9 s) by animals treated with highest dose however, the difference was not significant. There is a biological plausibility that chronic khat use may induce memory deficits and impair cognitive flexibility. The differential patterns of memory deficits may reflect the differences in dose effect as well as time dependent impairment.

Effect of Catha edulis (khat) on behaviour and its potential to induce seizures in Sprague Dawley rats.

BACKGROUND: Khat is a plant whose young shoots and leaves are habitually used in Eastern Africa and the Arabian Peninsula as a drug of recreation. Although it is used without any control in these regions, it contains two controlled substances, cathinone (schedule I) which is present in fresh khat and cathine (schedule VI) which is a degradation product of cathinone abundant in old khat. OBJECTIVE: To determine the effect of khat on locomotor behaviour and seizures in rats. DESIGN: Experimental study. SETTING: University of Nairobi. SUBJECTS: Adult male rats in groups of six were given fresh khat, old khat, methylphenidate and saline at varying doses and observed over three hours. RESULTS: Fresh khat at low doses and old khat at high doses stimulated locomotor activity. High doses of fresh and old khat induced stereotype behaviour and seizures. CONCLUSION: The results show that khat stimulates locomotor and stereotypic behavioural activity and can induce seizures; results similar to those observed with amphetamine analogs.

Emerging picture of multiple sclerosis in Kenya.

OBJECTIVE: To report on the occurrence of clinical multiple sclerosis among indigenous Bantu African Kenyans who have never been out of the country. DESIGN: A retrospective study. SETTING: A private neurology and clinical electrophysiology clinic. SUBJECTS: All the patients referred to the clinic by neurologists and other specialists for electrophysiological tests with diverse neurological complaints. The patients examined and diagnosed as having multiple sclerosis on clinical grounds and established criteria are reported. RESULTS: Out of 2831 patients referred for electrophysiological tests over a ten year period, nine patients were diagnosed as having definite multiple sclerosis on clinical grounds. Four of these had supporting laboratory findings (MRI scans, CSF studies and visual evoked responses). The presenting symptoms were predominantly visual disturbances and somatic sensorimotor disturbances which were seen in all the patients. Cerebellar dysfunction was observed less frequently, in less than half of the patients while sphincter disturbances were conspicuously rare. The sex distribution was overwhelmingly in favour of the female at a ratio of 7:2. A part from two patients of Indo-asian ethnicity, all the others were indigenous Bantu Africans who had never travelled outside their country before the onset of the illness. CONCLUSIONS: Multiple sclerosis occurs amongst Bantu Africans and may not be as rare as previously suggested and its prevalence is certainly on the increase. The development of higher incidence rates in communities where the illness was previously unknown may present opportune settings for the study of aetiological factors of this illness as it emerges. There is a need therefore for proper epidemiological studies to evaluate these factors, especially environmental factors, as the new disease continues to appear.

Pathophysiology and management of pain

Pain is the commonest sympton of disease and as such has a most prominent position in the diagnosis of disease. Most doctor training curricula emphasise this aspect of pain (that is; its diagnostic value) but little attention is given to the individual's cultural and psychological make-up that influence its severity and the indiviudal's ability to cope with it. For this reason; management of pain has not been given the attention it deserves and common treatment regimes and plans appear ritualistic and hardly ever give sufficient consideration to the patient's needs. The development of chronic pain requires more detailed management plan and all aspects of the patient should be considered including: the clinical; aetiological and pathological diagnosis; psychosocial make up; emotional and motivational background; the expected duration of illness; othere intercurrent illnesses and other concomitant treatments. The management of the hysteriacal patient must essentially be different from that of a hypochondriac. The mechnaisms underlying the pain; whether in the peripheral sensory apparatus or the cental circuitry subserving pain; the neural pathways of pain; the inherent pain mechanisms; and the endogenous pain relieving mechanisms; need to be understood ideally before formulating a treatment plan. The role played by local and peripheral factors at the site of injury; by nerve growth factors; cytokines and others in the development of physiological and anatomical recruitment; so central to chronic pain; are also fundamental towards management; especially in the exploration for ways of preventing the development of chronic pain. Exploitation of these mechanisms and the effective use of drugs appropriately and in the right doses supportyed by physical and psychological methods would go a long way in alleviating the problem of unecessary pain so common in clinical practise. This communication deals mainly with the pathophysiological mechanisms in the development of chronic pain and possible approaches to its management

Peripheral neuropathy in AIDS patients at Kenyatta National Hospital.

Between June and December 1992 forty AIDS patients as defined by the CDC criteria, admitted to the medical wards of the Kenyatta National Hospital, were studied to determine the prevalence and pattern of peripheral neuropathy. Their mean age was 33 +/- 3 years with a range of 16 to 55 years. Clinical and laboratory assessment were carried out both to confirm peripheral neuropathy and exclude other causes of peripheral neuropathy apart from AIDS. All the patients had nerve conduction and electromyographic studies done. Eighteen patients were asymptomatic while fourteen had both signs and symptoms. The commonest symptom was painful paresthesiae of the limbs (35%) while the commonest sign was loss of vibration sense (60%). When symptoms, signs, and electrophysiological studies were combined, all the patients fitted the definition of peripheral neuropathy. The commonest type of peripheral neuropathy was distal symmetrical peripheral neuropathy (DSPN) (37.5%).

PIP: In Kenya, physicians evaluated 40 AIDS patients admitted to Kenyatta National Hospital during June-December 1992 to determine the prevalence and types of peripheral neuropathy in AIDS patients. 75% were 21-40 years old. 18 (45%) of the 40 AIDS patients had symptoms of peripheral neuropathy. Symptoms included increased sensitivity to stimulation (43%), hyperpathia (15%), and muscle or limb weakness (13%). 26 AIDS patients had signs of peripheral neuropathy, especially impaired sense of vibration (60%). 14 of these patients had both signs and symptoms. Electromyographic and nerve conduction velocity revealed peripheral neuropathy in 16 (40%) AIDS patients. The types of peripheral neuropathy included distal symmetrical peripheral neuropathy (37.5%), polyneuropathy, and mononeuritis multiplex. When the symptoms, signs, and electroneurophysiological test findings were considered, all 40 AIDS patients had evidence of peripheral neuropathy.

Autonomic nervous function in patients with chronic renal failure at the Kenyatta National Hospital.

Autonomic nervous function was assessed in twenty two patients (16 males and 6 females) with chronic renal failure on conservative management. The presenting symptoms were postural dizziness in 10(45%), impotence in 4(18%) patients and 1 patient each with diplopia, urinary urgency and nocturnal diarrhoea. The following autonomic function tests were performed; valsalva manoeuvre, heart rate response to deep breathing, heart rate response to posture and postural change in blood pressure. Fifteen (68%) patients had abnormal autonomic function tests. Out of these patients, 14(93%) had abnormalities of the parasympathetic system and only one had abnormalities in the sympathetic system. There was a negative correlation between the creatinine levels and the following; valsalva ratio (r = -0.72 p < 0.001), heart rate response to standing (r = -0.56 p < 0.01) and heart rate response to deep breathing (r = -0.45 p < 0.05).

The effects of amrinone on platelet count, survival and function in patients with congestive cardiac failure.

In a prospective trial, the immediate and long-term haematological effects of amrinone were studied in sixteen patients with refractory cardiac failure. The platelet count was significantly and variably reduced in all patients and the reduction was related to log plasma amrinone concentration. Platelet survival was significantly reduced in those cases studied. No evidence of disseminated intravascular coagulation or intravascular platelet deposition was observed and the reduced platelet survival was not considered to be the result of an immunological process. Evidence of a marrow response to the reduced platelet count and survival was seen. Although no haemorrhagic symptoms were observed in the patients, the haematological side-effects were considered to be of such severity as to limit the use of this drug in clinical practice.