Taher Ba-Omar

Effects of pesticide temephos on the gills of Aphanius dispar (Pisces: Cyprinodontidae).

The changes in the behavior of Aphanius dispar, a cyprinodont fish when exposed to different concentrations of temephos, an organophosphorus pesticide widely used to control mosquito larvae in aquatic habitats are noted. The histopathology of gills exposed to temephos is studied in detail using light microscopy (LM), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The gill lesions were seen in all exposed concentrations of 1, 5, 10 and 25 ppm and the magnitude of the damage increased with the increase in concentrations. The most adverse effects of temephos are the destruction of cartilage and the large-scale cell death. Other effects included the degradation of chloride cells (CCs), desquamation, epithelial lifting, hypertrophy and lamellar fusion. The histological changes of microridges did not follow a consistent pattern in exposed concentrations. However, lamellar curling and collapsing was common in all exposed fish.

Effect of deltamethrin on the gills of Aphanius dispar: A microscopic study

Aphanius dispar, a freshwater fish (mean total length±sd, 3.42±0.33 cm) was exposed to different concentrations of deltamethrin (2.25, 2.50 and 3.00 μg L(-1)), an insecticide used to control Dubas bug, Ommatissus lybicus in Oman. The histopathological changes in the structure of the gills in fish exposed to deltamethrin was studied using light, transmission and scanning electron microscopy. In light microscopy, the fish exposed to 2.25 μg L(-1) deltamethrin, showed hypertrophy and hyperplasia of chloride cells, while in 2.50 μg L(-1), additional changes like vacuolization, lifting of the lamellar epithelium and fusion of secondary lamellae were observed. The most severe alteration including vacuolization, desquamation of cells and dilation of intercellular space was recorded at 3.00 μg L(-1). Transmission and scanning electron microscopy, supports the findings of light microscopy and further document the ultrastructural damage caused, especially in exposure to 2.50 and 3.00 μg L(-1). Al l changes observed are described in detail. The deltamethrin exposure concentration of 2.25 μg L(-1) seems to be a threshold above which any small increase in concentration results in severe damage. All present results have been compared with those of previous studies on gill damage caused by various chemical substances. The impacts of the damage on the functioning of gills as a respiratory organ are discussed.

First report of Albizia lebbeck dieback caused by Scytalidium dimidiatum in Oman.

Over 200 Albizia lebbeck trees at Sultan Qaboos University campus wilted and died. The symptoms were dieback of large branches due to infection by Scytalidium dimidiatum. The fungus has also infected Ficus benghalensis, F. carica, F. retusa, Thespesia populnea, Delonix regia and Peltophorum petrocarpum. This is the first report of the fungus in Oman and on A. lebbeck, T. populnea, D. regia and P. petrocarpum. The strain of this fungus has not been found to cause human disease in Oman.

Ultrastructural features and elemental distribution in eggshell during pre and post hatching periods in the green turtle, Chelonia mydas at Ras Al-Hadd, Oman

Eggshells were randomly collected from turtle nests immediately after oviposition and at the end of incubation to examine the ultrastructural features using scanning JSM-5600LV microscopy. Three layers were recognized; an outer calcareous, a middle multistrata and an inner membrane. The calcareous layer had loose nodular units varying in shape and size without interlocking attachments. In freshly laid eggs, each nodular unit had spicules arranged in folded stacks. The spicules became unfolded during incubation, to form radiating configurations. Elemental composition and mapping of the layers were analyzed using energy dispersive spectroscopy (EDS). The elements were unevenly distributed throughout the eggshell and Ca(2+) decreased significantly after hatching. X-ray diffraction was used to identify the crystals of the eggshells. It revealed that nodular units of the calcareous were made up of CaCO(3), as aragonite (91%), calcite (6%) and vaterite (3%). The middle layer consisted of organic amorphous material with aragonite (89%) and calcite (11%). The shell membrane consisted of reticular fibers with crystals predominantly of NaCl halite. Thermogravimetry analysis of the calcareous layer indicated a complete evaporation of bonded H(2)O at 480 degrees C and CO(2) at 830 degrees C. Using the differential thermal analysis (DTA), aragonite was transformed to stable calcite at 425 degrees C.

Liver and kidney toxicity induced by Afzal smokeless tobacco product in Oman.

Afzal, the common smokeless tobacco product (STP) in Oman, is believed to contain toxins that may impair the function of some organs such as liver and kidney. An aqueous extract from Afzal was added to drinking water to be administrated orally to Wistar albino rats (n=72) young and adult from both genders weighing between 60-80g and 150-240g respectively for 8 weeks. Animals were divided into three groups: control (distilled water instead of Afzal extract), low-dose (3mgnicotine/kgbodyweight/day) and high-dose (6mgnicotine/kgbodyweight/day). The animals were euthanized and their blood, liver and kidney were collected for biochemical and histopathological investigations. Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were assayed for the liver function, while blood urea nitrogen (BUN) and creatinine (CRT) were assayed for the kidney function. The results showed a significant increase in the ALT, AST, BUN and CRT levels (P<0.05) in both Afzal-treated groups (low and high doses) compared with the control. Histopathological findings revealed the initial but seem to be serious degenerative alterations of periportal fibrosis in liver and edematous and calcified changes in renal glomerulus among Afzal-treated groups. Additionally, the weight gain of the Afzal-treated groups was lower than the control group. Our findings show that the exposure of Wistar rats to the Afzal extract has the potentials of causing decreased weight gain and dose-dependent functional and structural damage to the biochemical and histological profiles of liver and kidney as well as serious biochemical effects.

Characterisation of nicotine and cancer-enhancing anions in the common smokeless tobacco Afzal in Oman

OBJECTIVES Afzal is a common smokeless tobacco product (STP) available illegally in Oman. This study aimed to assess pH and moisture levels and determine cancer-enhancing factors in a randomly selected sample of Afzal. METHODS This study was carried out at the Sultan Qaboos University in Muscat, Oman, between April and December 2013. A package of Afzal was purchased from a single provider and divided into samples. The pH and moisture content of the samples were measured according to the protocols of the Centers for Disease Control and Prevention. Gas chromatography-mass spectrometry was used to analyse nicotine levels and ion-exchange chromatography (IC) was used to determine concentrations of nitrate, nitrite, chloride, fluoride, bromide, sulphate and phosphate anions. RESULTS The samples had an alkaline pH of 10.46 with high levels of total (48,770.00 µg per g of STP [µg/g]) and unionised (48,590.00 µg/g) nicotine. The concentration of nitrate (8,792.20 µg/g) was alarmingly high. The chloride concentration (33,170.80 µg/g) showed a surge on IC chromatography. The moisture content percentage was 52.00%. CONCLUSION The moisture content percentage and chloride concentration of Afzal was consistent with those of other STPs. In contrast, nitrite, sulphate and phosphate concentrations were below reported levels of other STPs. All anion concentrations were below the maximum daily limit set by international health organisations. However, the high concentrations of nitrite, nitrate and nicotine and the elevated alkaline pH observed in the analysed Afzal samples suggest that STP users will face health risks as a result of their use.

Emergence pattern of the Green Turtle, Chelonia mydas, hatchlings under laboratory and natural conditions

Abstract Green Turtle eggs were collected at random from 5 different nests from the Ras Al-Hadd Reserve in Oman. They were incubated 16hr after oviposition at constant temperatures set at 30–31°C for female producers and at 26–27° for male producers. Standard histological procedure of the gonads was performed for sex determination. Despite the constant temperatures set in the incubators, there were differences among the incubated eggs. This is similar to the natural condition, where an asynchronous pattern of emergence is common. Pipping occurs when the eggshell has a slit and hatching is when the head and one flipper are outside the eggshell. Emergence occurs when the hatchling is completely free from the extraembryonic membranes and eggshell. There was no correlation between the pipping-hatching and hatching-emergence intervals in the female, but in males the two intervals were significantly correlated (P<0.01). Hatchling weights were: 28.22 g (±0.83) for females and 25.74 g (±0.58) for males. In both sexes, hatchling weight did not influence the duration of the two intervals. The duration between pipping emergence was significantly (P<0.01) longer in females than in males. Natural and incubator observations showed that the hatchlings remained in the nest after emergence for at least 48hr until the umbilical swelling had subsided before attempting their emergence escape. While the hatchlings remain inside the eggshell after pipping attached to chorioallontoic/amniotic membranes, they are occasionally vulnerable to injury by nesting turtles, micro-organisms or early-emerged hatchlings inside the nest.

Embryonic and larval staging of the Arabian Toad, Bufo arabicus (Amphibia: Bufonidae)

Abstract The development of Bufo arabicus, is described here from the zygote to the newly metamorphosed toadlet. The ontogeny of B. arabicus is arranged into successive stages numbered 1–45. These include the zygote (stage 1), cleavage (stages 2–6), blastula (stages 7–8), gastrulation (stages 9–11), the neurulation stages (stages 12–15), embryonic development (stages 16–23), larval period (stages 24–41), metamorphosis (stages 42–44) and the juvenile/toadlet (stage 45). The description of the developmental stages is based on the external morphological and physiological characteristics and is accompanied by photographs. The stages in the present table for the development of B. arabicus are compared with normal tables of the genus Bufo and other anuran species. The development of B. arabicus resembles very closely that of other Bufo spp. Minor differences can be seen between the different staging tables of different species because of variations in methods of staging and the criteria on which the table was based. One special feature is that B. arabicus hatches early (stage 15) compared to other reported bufonids.

Analysis of Tobacco-Specific Nitrosamines in the Common Smokeless Tobacco Afzal in Oman

OBJECTIVES There is a lack of awareness regarding the carcinogenicity of Afzal, an illegal smokeless tobacco product (STP) widely used among the Omani youth. Previous research has shown that certain types of tobacco-specific nitrosamines (TSNAs) are associated with oral and lung cancers. This study therefore aimed to assess levels of four common TSNAs in a randomly selected sample of Afzal. METHODS This study was carried out at Sultan Qaboos University in Muscat, Oman, between April and September 2013. A random sample of Afzal was analysed for four types of TSNAs using high-performance liquid chromatography-tandem mass spectrometry. The four types of TSNAs analysed were 4-(N-nitrosomethylamino)-1-(3-pyridyl)-1-butanone (NNK), N-nitrosonornicotine (NNN), N-nitrosoanatabine (NAT) and N-nitrosoanabasine (NAB). As a reference product, a sample of laboratory-manufactured American moist snuff (Centers for Disease Control and Prevention, Atlanta, Georgia, USA) was also used to confirm the accuracy and precision of the analysis. RESULTS The analysis revealed total TSNA levels of 3.573 μg/g in the Afzal sample. Mean levels of NNN, NNK, NAT and NAB were 1.205, 1.015, 0.809 and 0.545 μg/g, respectively. CONCLUSION Levels of the two most abundant TSNAs (NNN and NNK) found in the Afzal sample exceeded international regulatory limits. Afzal users therefore need to be educated regarding the potential health risks associated with their STP use. Stricter implementation of current legislation is recommended to reduce the availability and usage of Afzal in Oman.

The Identification of Pompe Disease Mutations in Archival Tissues and Development of a Rapid Molecular-based Test

OBJECTIVES Pompe disease (glycogen storage disease type II) is a rare autosomal recessive lysosomal storage disease that is caused by acid alpha-glucosidase deficiency. Early enzyme replacement therapy can benefit infants with the disease but the diagnosis is complicated by the rarity of the disease and the heterogeneity of the clinical manifestations. In this study, DNA extracted from archival postmortem formalin-fixed paraffin-embedded tissues was used to identify Pompe disease mutations in Oman and develop a rapid molecular-based test. METHODS Intronic primers were designed to amplify short fragments (193-454 base pairs [bp]) from coding exons (2-20) and screen for mutations using direct sequencing (DS). RESULTS Two mutations known to cause severe disease were identified in two samples. One was a coding mutation, c.2560C>T (p.Arg854X), and the second was found at a splice acceptor site, c.1327-2A>G. Polymerase chain reaction- and restriction fragment length polymorphism-based tests were designed for the rapid genotyping of the identified mutations. CONCLUSION These tests can facilitate prenatal diagnosis and help in identifying carriers in families with the identified mutations.