Background The genetic composition of cynomolgus macaques used in biomedical research is not as well-characterized as that of rhesus macaques. Methods Populations of cynomolgus macaques from Sumatra, Corregidor, Mauritius, Singapore, Cambodia and Zamboanga were analyzed using 24 STRs. Results The Sumatran and Cambodian populations exhibited the highest allelic diversity while the Mauritian population exhibited the lowest. Sumatran cynomolgus macaques were the most genetically similar to all others, consistent with an Indonesian origin of the species. The high diversity among Cambodian animals may result from interbreeding with rhesus macaques. The Philippine and Mauritian samples were the most divergent from other populations, the former due to separation from the Sunda Shelf by deep water and the latter due to anthropogenic translocation and extreme founder effects. Conclusions Investigators should verify their research subjects’ origin, ancestry and pedigree to minimize risks to biomedical experimentation from genetic variance stemming from close kinship and mixed ancestry as these can obscure treatment effects.

In the past decade, many researchers have published papers about hybridization between long-tailed and rhesus macaques. These previous works have proposed unidirectional gene flow with the Isthmus of Kra as the zoogeographical barrier of hybridization. However, these reports analyzed specimens of unknown origin and/or did not include specimens from Thailand, the center of the proposed area of hybridization. Collected specimens of long-tailed and rhesus macaques representing all suspected hybridization areas were examined. Blood samples from four populations each of long-tailed and rhesus macaques inhabiting Thailand, Myanmar, and Laos were collected and analyzed with conspecific references from China (for rhesus macaques) and multiple countries from Sundaic regions (for long-tailed macaques). Ninety-six single nucleotide polymorphism (SNP) markers specifically designed to interrogate admixture and ancestry were used in genotyping. We found genetic admixture maximized at the hybrid zone (15-20°N), as well as admixture signals of varying strength in both directions outside of the hybrid zone. These findings show that the Isthmus of Kra is not a barrier to gene flow from rhesus to long-tailed populations. However, to precisely identify a southernmost barrier, if in fact a boundary rather than simple isolation by distance exists, the samples from peninsular Malaysia must be included in the analysis. Additionally, a long-tailed to rhesus gene flow boundary was found between northern Thailand and Myanmar. Our results suggest that selection of long-tailed and rhesus macaques, the two most commonly used non-human primates for biomedical research, should take into account not only the species identification but also the origin of and genetic admixture within and between the species.

Background: Plasmodium knowlesi and Plasmodium cynomolgi are two malaria parasites naturally transmissible between humans and wild macaque through mosquito vectors, while Plasmodium inui can be experimentally transmitted from macaques to humans. One of their major natural hosts, the long-tailed macaque (Macaca fascicularis), is host to two other species of Plasmodium (Plasmodium fieldi and Plasmodium coatneyi) and is widely distributed in Southeast Asia. This study aims to determine the distribution of wild macaques infected with malarial parasites by examining samples derived from seven populations in five countries across Southeast Asia.Methods: Plasmodium knowlesi, P. cynomolgi, P. coatneyi, P. inui and P. fieldi, were detected using nested PCR assays in DNA samples from 276 wild-caught long-tailed macaques. These samples had been derived from macaques captured at seven locations, two each in the Philippines (n = 68) and Indonesia (n = 70), and one each in Cambodia (n = 54), Singapore (n = 40) and Laos (n = 44). The results were compared with previous studies of malaria parasites in longtailed macaques from other locations in Southeast Asia. Fisher exact test and Chi square test were used to examine the geographic bias of the distribution of Plasmodium species in the macaque populations. Results: Out of 276 samples tested, 177 were Plasmodium-positive, with P. cynomolgi being the most common and widely distributed among all long-tailed macaque populations (53.3 %) and occurring in all populations examined, followed by P. coatneyi (20.4 %), P. inui (12.3 %), P. fieldi (3.4 %) and P. knowlesi (0.4 %). One P. knowlesi infection was detected in a macaque from Laos, representing the first documented case of P. knowlesi in wildlife in Laos. Chi square test showed three of the five parasites (P. knowlesi, P. coatneyi, P. cynomolgi) with significant bias in prevalence towards macaques from Malaysian Borneo, Cambodia, and Southern Sumatra, respectively. Conclusions: The prevalence of malaria parasites, including those that are transmissible to humans, varied among all sampled regional populations of long-tailed macaques in Southeast Asia. The new discovery of P. knowlesi infection in Laos, and the high prevalence of P. cynomolgi infections in wild macaques in general, indicate the strong need of public advocacy in related countries.

INTRODUCTION Xanthogranulomatous cholecystitis (XGC) is an uncommon variant of chronic cholecystitis characterised by marked thickening of the gallbladder wall and dense local adhesions. Pre-operative and intra-operative diagnosis is difficult and it often mimics a gallbladder carcinoma (GBC). Laparoscopic cholecystectomy (LC) is frequently unsuccessful with a high conversion rate. A series of patients with this condition led us to review our experience with XGC and to try to develop a care pathway for its management. PATIENTS AND METHODS A retrospective review of the medical records of 1296 consecutive patients who had undergone cholecystectomy between January 2000 and April 2005 at our hospital was performed. Twenty-nine cases of XGC were identified among these cholecystectomies. The clinical, radiological and operative details of these patients have been analysed. RESULTS The incidence of XGC was 2.2% in our study. The mean age at presentation was 60.3 years with a female:male ratio of 1.4:1. Twenty-three patients (79%) required an emergency surgical admission at first presentation. In three patients, a GBC was suspected both radiologically and at operation (10.3%), but was later disproved on histology. Seventeen patients (59%) had obstructive jaundice at first presentation and required an endoscopic retrograde cholangiopancreatography (ERCP) before LC. Of these, five had common bile duct stones. Abdominal ultrasound scan showed marked thickening of the gallbladder wall in 16 cases (55%). LC was attempted in 24 patients, but required conversion to an open procedure in 11 patients (46% conversion rate). A total cholecystectomy was possible in 18 patients and a partial cholecystectomy was the choice in 11 (38%). The average operative time was 96 min. Three patients developed a postoperative bile leak, one of whom required ERCP and placement of a biliary stent. The average length of stay in the hospital was 6.3 days. CONCLUSIONS Severe xanthogranulomatous cholecystitis often mimics a gallbladder carcinoma. Currently, a correct pre-operative diagnosis is rarely made. With increased awareness and a high index of suspicion, radiological diagnosis is possible. Preoperative counselling of these patients should include possible intra-operative difficulties and the differential diagnosis of gallbladder cancer. Laparoscopic cholecystectomy is frequently unsuccessful and a partial cholecystectomy is often the procedure of choice.

Macaques are commonly used in biomedical research as animal models of human disease. The ABO phenotype of donors and recipients plays an important role in the success of transplantation and stem cell research of both human and macaque tissue. Traditional serological methods for ABO phenotyping can be time consuming, provide ambiguous results and/or require tissue that is unavailable or unsuitable. We developed a novel method to detect the A, B, and AB phenotypes of macaques using real-time quantitative PCR. This method enables the simple and rapid screening of these phenotypes in macaques without the need for fresh blood or saliva. This study reports the distribution of the A, B, and AB phenotypes of captive cynomolgus macaques that, while regionally variable, closely resembles that of rhesus macaques. Blood group B, as in rhesus macaques, predominates in cynomolgus macaques and its frequency distribution leads to a probability of major incompatibility of 41%. No silencing mutations have been identified in exons 6 or 7 in macaques that could be responsible for the O phenotype, that, although rare, have been reported. The excess homozygosity of rhesus and cynomolgus macaque genotypes in the present study, that assumes the absence of the O allele, suggests the possibility of some mechanism preventing the expression of the A and B transferases.