Khat Abuse in Yemen: A Population-Based Survey

Khat is a centuries old substance of abuse produced on a large scale in Yemen. Beta-ketoamphetamine, otherwise called cathinone, is the main contributor to the stimulant effect of khat. A recent unpublished study from Yemen found that the percentage of native users may be as large as 70%. The objective of the current study was to evaluate this figure, to study users' personal characteristics in order to find out whether there are subgroups, particularly, at risk of abuse, and to assess the immediate adverse effects of the compound as well as the main motivations for abuse. The entire population of a randomly selected district of Yemen's capital city Sana'a was used. Self-administered questionnaires were applied. Of 600 questionnaires distributed only 200 were completed and usable. One hundred fifty nine persons (80%) were users. Eighty-six percent of the males and 50% of the females were users ( p < 0.001). The majority of the users were between 15 and 30 years old. The numbers of females and males in different age classes were similarly distributed. Daily adverse effects included tiredness, gastrointestinal and cardiac complaints, and headache occurring in between 38 and 85% of the users (95% confidence interval). The main reasons for chewing khat was for accomplishing study and hard work in the males and attending social events in the females (difference between genders at p < 0.05). Our study shows that about 80% of the Yemeni people use khat on a daily basis. The proportion of male users is larger than that of females. This may be a consequence of the dominant role of the males in the Yemeni society. Both time and money are lost among users, which must affect their lifes profoundly. This is particularly serious because the majority of users are between 13 and 30 years and thus in an active age of life. Khat has a wide range of unpleasant daily side effects and enhances the risks of infectious diseases. Studying serious adverse effects was not the objective of our survey but many case reports are currently being published.     

Contrasting sensitivities to toxicants of the freshwater amphipods Gammarus pulex and G. fossarum

Amphipods are an important component of freshwater ecosystems. They are very often used in ecotoxicology, particularly the freshwater amphipod Gammarus pulex. However, there is scarce information on the sensitivity to toxicants of other species within the genus Gammarus. The present study aims to: (1) to compare sensitivities to ivermectin and cadmium between two species of freshwater amphipods (G. pulex and G. fossarum); (2) to compare sensitivities to these toxicants between juveniles and adults within each species; and (3) to assess whether the sensitivity to toxicants of these co-generic species is related with the wideness of their natural distribution area. Eight independent short-term bioassays (96 h) were conducted to assess sensitivity for ivermectin and cadmium for juvenile and adult life stages for each species. The LC50 (mortality) and EC50 (mortality plus immobility) were calculated to 48 and 96 h of continuous exposure. Our results showed that G. pulex was less tolerant to ivermectin than G. fossarum, the reverse being true for cadmium. In general, juveniles of both species were less tolerant to cadmium than adults. In the case of ivermectin, only for G. fossarum EC50 values were different between life stages. These results suggest that the risk assessment of toxicants to freshwater amphipods should include bioassays with the most sensitive species and life stage.     

Effects of Benzo(a)pyrene and Size of Organic Matter Particles on Bioaccumulation and Growth of Asellus aquaticus

The effects of sediment-bound toxicants to aquatic invertebrates may vary due to differences in bioavailability, food quality, or food structure. The equilibrium partitioning theory (EPT) assumes that organic matter content of sediments and not structure of organic matter is relevant for biological effects of polycyclic aromatic hydrocarbons. To test this hypothesis effects of benzo(a)pyrene (B(a)P) and size of sediment organic matter particles on the bioaccumulation and growth of the waterlouse Asellus aquaticus were studied in laboratory microcosms. Sediments and A. aquaticus were both sampled in an unpolluted, spring-fed pond. The sampled sediment was divided into two portions. From one portion the size of the organic matter particles was mechanically reduced. One set of each sediment fraction (fine and coarse) was spiked with B(a)P and incubated for 3 weeks resulting in a concentration of 70 mg B(a)P per kg sediment. Bioassays of 32 days were performed in a 2 × 2 factorial design with four replicas of each treatment. The results showed that the growth of A. aquaticus was mainly influenced by the size of organic matter particles. Growth was significantly less (27%) on finer sediments than on coarser sediments. The increase in length was 9–14% lower in the spiked sediments, but this difference was not significant. The reduced growth of A. aquaticus on finer sediments may be due to a change in the availability and/or quality of food together with a change in feeding behavior. The coarse and fine spiked sediment types did not differ significantly with respect to the sediment water partition coefficient, the organic carbon water partition coefficient, and the bioconcentration factor. In contrast, the biota to sediment accumulation factors were significantly 15% higher in the cosms with coarse sediments than in cosms with fine sediments. However, this difference is too small to conflict with EPT. Received: 9 November 1999/Accepted: 3 May 2000     

Prognostic Significance of Bone Marrow Trephine and Peripheral Blood Smears in 55 Patients with Mantle Cell Lymphoma

Bone marrow trephine and peripheral blood smears taken at diagnosis of 55 cases of well-documented mantle cell lymphomas were reviewed in order to analyse the leukaemic involvement in this non-Hodgkin's lymphoma: its incidence, morphological characteristics and prognostic significance. A median survival of 36 months was found. The median age was 61 and the male to female ratio was 4:1. Morphologically 7 cases presented with a mantle zone pattern, all the others had a diffuse pattern. Involvement of the bone marrow was found in 58% and a trend for prolonged survival in patients with a negative trephine was seen. An absolute lymphocytosis above 10,000 μ1 was found at diagnosis in 5 cases (10%) and had a statistically significant impact on survival. An additional 5 cases developed frank leukaemia during the course of the disease and died within 1 to 6 months of this evolution, suggesting that marked lymphocytosis is more a terminal event associated with an extremely poor prognosis than a presenting symptom. Finally we identified an additional parameter with statistically prognostic significance, namely, the presence of atypical cells in the peripheral blood even in the absence of an increased lymphocytosis.     

Treatment of vaginal candidosis with oral ketoconazole

Results with ketoconazole were studied in 281 non-pregnant patients with acute and chronic Candida-vaginitis. Several dose regimens were evaluated. The 5-day regimens (200 mg b.i.d. or 400 mg once daily) seem to be the most appropriate schedules in this infection. Side effects were minor. Relapse rates are not different from those, historically known, with topical antifungals.     

Blood flow to fetal organs as a function of arterial oxygen content

In a sheep preparation the blood flow to fetal organs was studied 3 to 10 days after surgery by means of the microsphere technique over a range of fetal arterial O2 content from 6 to 1 mM. Blood flows to neural tissues (cerebrum, cerebellum, brain stem), heart, and the adrenals increased in inverse relation to arterial O2 content. As a result the arterial supply of O2 to these organs tended to remain constant over the O2 range studied. Blood flow to the fetal lungs decreased progressively with hypoxia. The blood flow to kidneys, digestive tract, pancreas, and carcass had a tendency to remain constant or increase gradually in the transition from high to moderately low levels of arterial O2 content and then to decrease abruptly in more severe hypoxia. Umbilical blood flow did not change systematically in relation to arterial O2 content.