Host specificity and foraging efficiency in blood-sucking parasite: feeding patterns of the flea<Emphasis Type="Italic"> Parapulex chephrenis</Emphasis> on two species of desert rodents

Parasite species can adapt to ecological, behavioral, physiological and biochemical traits of a particular host species. The flea Parapulex chephrenis occurs on the spiny mouse Acomys cahirinus, but does not occur on a co-existing gerbil, Gerbillus dasyurus. To test the hypothesis that the host species affects feeding parameters of a host-specific flea, we studied the feeding rate, rate of blood digestion and resistance to starvation of P. chephrenis when feeding on A. cahirinus and G. dasyurus. We predicted that P. chephrenis would: (1) fill its gut with blood faster, (2) digest blood for a shorter time, and (3) survive longer when starved while feeding on its specific host, A. cahirinus, than on a non-specific host, G. dasyurus. These three responses were observed when P. chephrenis fed on the different hosts and, consequently, our predictions were supported. Twenty percent of fleas filled their midgut after feeding for 10 min on A. cahirinus but this occurred only after 25 min on G. dasyurus. The middle stage of blood digestion was significantly shorter in all fleas feeding on A. cahirinus than in fleas feeding on G. dasyurus. Flea survival was shorter when feeding on G. dasyurus than when feeding on A. cahirinus at 25 degrees C, but no difference in survival time was found at 15 or 20 degrees C. Both A. cahirinus, the specific host, and G. dasyurus, the non-specific host, co-exist in rocky habitats, yet P. chephrenis occurs on one rodent and not the other. The absence of P. chephrenis on G. dasyurus in nature and the decreased foraging efficiency when feeding on this species in the laboratory suggests that some physiological and biochemical differences between hosts can lead to sharp ecological differences in host-parasite relationships.     

Extensive digestive caustic burns: what are the limits for resection? A series of 12 patients

AIM OF THE STUDY: To report the results of oesogastric resections extended to surrounding organs following caustic ingestion, and to precise indications for resection and results of reconstruction. PATIENTS AND METHODS: From 1988 to 2001, 12 patients underwent oesophago-gastrectomy, extended to duodenum and pancreatic head (n = 6), jejunum (n = 4), colon (n = 2), spleen (n = 2) or pancreatic body (n = 1). Early morbidity and mortality, specificities of reconstruction, and quality of oral feeding were assessed retrospectively. RESULTS: Mean intensive care unit stay was 50 days (range: 16-152 days). All patients developed complications. Six patients were reoperated for secondary extension of caustic burns, mainly to colon (n = 4), small bowel (n = 2) and pancreas (n = 2). Three patients died on postoperative days 17, 20, and 130. Secondarily, eight patients (75%) underwent a substernal right ileocoloplasty. Six patients (50%) survived initial resection, and esophageal reconstruction. After a mean follow-up of 35 months (range: 7-87 months), four patients (33%) eat normally. CONCLUSIONS: After caustic burn, oesogastric resections extended to surrounding organs are associated with high morbidity and mortality. However, return of normal oral feeding can be expected in 33% of cases. Secondary extension of caustic burns to adjacent organs is a common eventuality, and may lead to prompt reintervention. Massive injury to small bowel or colon may compromise digestive function or secondary esophageal reconstruction, and thus may be the reasonable limit for resection.     

Precise intraoperative location of gastrointestinal bleeding with a hand-held counter. Work in progress

The nuclear medicine bleeding scan is frequently insufficient to locate sites of bleeding precisely, in spite of its great sensitivity. A small, hand-held Geiger-Müller counter, placed directly on exposed intestine in the operating room, enables precise location of the probable bleeding site. In three patients, the technique allowed a minimal amount of intestine to be resected, distinguished between large- and small-intestinal hemorrhage, and eliminated other foci as sites of bleeding.     

Primary malignant melanoma of the esophagus

Primary malignant melanoma of the esophagus is a rare but aggressive tumor that accounts for less than 0.1-0.2% of all esophageal malignancies. The aim of this study was to report a case of primary malignant melanoma of the esophagus in a 72-year-old woman. The diagnosis was histologically proven, but the patient died despite extensive surgical resection.     

Treatment of hypogonadal adolescent boys with long acting subcutaneous testosterone pellets

AIMS: Long acting subcutaneous testosterone pellets are of proved efficacy for the treatment of hypogonadal men, but have not been reported as a treatment modality in adolescent boys. Pharmacodynamic studies of subcutaneous testosterone release have shown prolonged normalisation of testosterone levels for at least four months. Administration of a long acting, safe, effective, and convenient form of treatment is desirable when life-long treatment is indicated. PATIENTS AND METHODS: Eighteen boys (aged 13.9-17.5 years at the start of treatment)-seven with primary hypogonadism, nine with secondary hypogonadism, and two boys being treated with testosterone for tall stature--were given testosterone pellets (8-10 mg/kg) every six months for 18 months. Height, weight, pubertal status, and psychosocial parameters were assessed and follicle stimulating hormone, luteinising hormone, testosterone, prolactin, and lipids were measured at 0, 1, 3, 6, 12, and 18 months. Bone age was measured at 0 and 12 months. RESULTS: In all boys growth velocity continued appropriately for bone age. Puberty continued to progress in all boys and in two boys the amount of virilisation exceeded that seen with previous treatment with intramuscular testosterone. After testosterone administration, follicle stimulating hormone and luteinising hormone suppressed incompletely in the boys with primary hypogonadism. Serum testosterone ranged from 4.3 to 26.7 nmol/l at three months to less than 10 nmol/l at six months after implantation. Prolactin and lipid levels were normal throughout the study. By report, there was an improvement in mood and emotional wellbeing. No pellet extrusions occurred in a total of 156 pellet insertions. CONCLUSIONS: All boys preferred this mode of testosterone administration to intramuscular injections. Long acting subcutaneous testosterone pellets are safe, efficacious, well tolerated, and convenient, and result in normal physical growth and improved psychological outlook in adolescent hypogonadal boys.     

Balo病同心圆硬化的MRI分析

目的：探讨Balo病同心圆硬化（BCS）的磁共振表现特征及其病理基础.方法：回顾性分析4例Balo病同心圆硬化患者的MRI表现,均经激素治疗临床症状好转后行MRI复查.结果：4例患者中,1例单发,3例多发,最多者病灶5个.病变主要累及大脑半球皮层下和深部白质区,共发现11个病灶,其中顶叶半卵圆中心和颞叶的发病比例高.典型同心圆样病灶8个,直径1～2.3cm,同心圆层数为3～5个.在T1WI加权像呈等、低信号相间;T2WI,FLAIR像上呈等、高信号交替环,病灶周围有轻度水肿表现,上述表现与镜下脱髓鞘区与髓鞘保留区相间相对应.其余3个不典型的病灶呈斑片状或煎蛋样改变;增强后1例病灶呈点状或边缘线状强化.结论：Balo病同心圆性硬化的MRI及其增强扫描具有特征性表现,可作为本病诊断的主要方法,并可用于疗效的观察.