Effects of graft pooling of foetal rat and mouse tissue and immunosuppression in the 6-hydroxydopamine rat model of Parkinson’s disease

 We employed intracerebral co-transplantation of foetal xenogeneic striatal mouse tissue and allogeneic rat substantia nigra into the adult rat brain to elucidate the effects of xenogeneic mouse graft on the function and survival of an allogeneic rat graft in 6-hydroxydopamine lesioned Sprague-Dawley rats. Foetal mouse striatum (STR) and rat substantia nigra (VM) were transplanted as non-pooled separate deposits or a pooled cell suspension with or without cyclosporin A (Cy A). Immunosuppressed recipients of pooled rat and mouse co-grafts showed a significantly better compensation of amphetamine-induced rotational behaviour compared with non-immunosuppressed animals with pooled rat and mouse co-grafts 3 and 6 weeks post-grafting.Tyrosine hydroxylase (TH) immunohistochemistry revealed a non-significant reduction in survival in pooled (1806.3±367.5 cells) rat and mouse co-transplants without immunosuppression compared with immunosuppressed pooled (3383.3±732.7 cells) animals with allo- and xenogeneic tissue and controls (3506.4±839.3 cells). Graft volumes were significantly reduced in pooled transplants without immunosuppression (0.1±0.026 mm³; ANOVA post-hoc SchefféF-test, P<0.0001) compared with immunosuppressed recipients (0.7±0.1 mm³) and controls (0.6±0.1 mm³). In non-pooled allo- and xenogeneic grafts without immunosuppression the survival rate of the TH-immunoreactive cells and graft volumes were reduced (2359.3±479.5 cells; 0.2±0.043 mm³) compared with immunosuppressed animals (2927.3±946.6 cells; 0.6±0.2 mm³) and controls (2701.1±693.8 cells; 0.3±0.1 mm³) without reaching a level of significance. Rejection of mouse tissue was observed in all non-immunosuppressed recipients. In summary: (i) continued immunosuppression yielded significant beneficial effects on function and beneficial effects on survival of pooled grafts with an immunogenetic disparity; (ii) the rejection of a xenogeneic graft component may compromise survival and function of other, allogeneic graft components; and (iii) transplantation of non-pooled allo- and xenogeneic tissues may result in a better survival of the graft compared with pooled cell suspensions. Received: 25 March 1996 / Accepted: 1 December 1996     

Lessons for the laboratory from a general practitioner survey.

AIMS: To assess the current performance of the clinical biochemistry service provided to general practitioners, with particular attention to result turnround times, and to identify and improvements required. METHODS: Postal questionnaire survey of general practitioners in the London Borough of Tower Hamlets who used the clinical biochemistry laboratory of the Royal London Hospital. A flow analysis study of turnround times for general practitioner samples was also performed. RESULTS: Responses to the questionnaire showed that although 82% of general practitioners thought the current quality of service provided was better than fair, the actual turnround times achieved were longer than the acceptable times required. There was also a strong demand (> 66% of responders) for additional information-such as highlighting of abnormal results-to be provided with results. There was wide variability between practitioners in their use of the laboratory (from none to > 800 requests per year), with no apparent correlation to practice size. Of the repertoire of tests requested, a surprisingly high percentage (14.3%) were for thyroid function. Flow analysis of turnround times for thyroid function tests showed that problems lay not with the time taken for analysis (only 7.8% of the total turnround time) but with the pre- and postanalytical phases, that is, the sample collection and results delivery service. CONCLUSIONS: Increasing the proportion of health care delivered in the primary care sector will inevitably increase the requirement for pathology services. Improvements in the specimen collection and results delivery service to general practitioners are needed to meet their expectations. It remains to be determined whether increased investment in these aspects of laboratory service would result in improved patient care in the primary sector.     

A proposed role for silicates and protein in the proliferative effects of saccharin on the male rat urothelium

High doses of sodium saccharin, a non-genotoxic chemical, lead to the formation of silicate-containing precipitate and microcrystals in urine of male rats. Differences in urinary protein, pH, sodium and other factors affect silicate-containing precipitate and microcrystal formation as well as the bladder effects of sodium saccharin. Total urinary silicon concentration (mostly soluble) in sodium saccharin-fed rats is similar to or lower than the concentration in control rats. Binding of saccharin to male rat urinary proteins was demonstrated by equilibrium-gel filtration. We propose that by binding to urinary proteins under appropriate conditions, saccharin produces a nidus for the formation of silicate-containing precipitate and crystals. These appear to be cytotoxic to the superficial bladder epithelium, with cell death resulting in regenerative hyperplasia. Factors that influence the formation of these silicate-containing materials might provide a rationale for sex, species, dose and dietary differences in response to sodium saccharin.     

Myofascial wrap to treat intractable urinary incontinence in children

Objectives. The management of intractable urinary incontinence in the patient with cloacal or bladder exstrophy/epispadias, failed bladder neck plasty, or failed augmentation cystoplasty remains a surgical challenge. The myofascial wrap, a modification of the rectus fascial wrap, was developed to treat intractable urinary incontinence due to sphincteric incompetence in these problematic cases. A full-thickness, vascularized pedicle of anterior rectus sheath, rectus abdominis muscle, and posterior rector sheath is incorporated into a bladder neck wrap to provide support, mucosal coaptation, and active muscular tone.Methods. Eight patients (5 females and 3 males) with total urinary incontinence due to sphincteric incompetence underwent the myofascial wrap. Urinary tract pathology included cloacal exstrophy (2), female epispadias (2), classic bladder exstrophy (1), male epispadias (1), myelomeningocele (1), and a pelvic tumor (1). The procedure is performed by harvesting a full-thickness strip of pedicled rectus muscle along with the anterior and posterior fascial sheaths. The strip is passed underneath and then over the bladder neck in a near 360° wrap. The free end of the wrap is anchored into the pubic bone in an ipsilateral subperiosteal pouch.Results. Six of the 8 patients are completely continent, and 2 patients void spontaneously without the need for catheterization.Conclusions. The myofascial wrap provides support, mucosal coaptation, and muscular tone to an incompetent sphincter and bladder neck. Favorable results in a very difficult population of pediatric patients warrant its continued use.     

Immunoglobulin mimicry by Hepatitis C Virus envelope protein E2

Hepatitis C virus (HCV) establishes persistent infection in the majority of infected individuals. The currently accepted hypothesis of immune evasion by antigenic variation in hypervariable region 1 (HVR1) of glycoprotein E2 does not however, explain the lack of subsequent immune recognition. Here, we show that the N-terminal region of E2 is antigenically and structurally similar to human immunoglobulin (Ig) variable domains. E2 is recognized by anti-human IgG antibodies and also possesses common amino acid (aa) sequence features of the conserved v-gene framework regions of human Ig light chains in particular but also heavy chains and T cell receptors. Using a position specific scoring system, the degree of similarity of HVR1 to Ig types correlated with immune escape and persistence in humans and experimentally infected chimpanzees. We propose a unique role for threshold levels of Ig molecular mimicry in HCV biology that not only advances our concept of viral immune escape and persistent infection but also provides insight into host-dependent disease patterns.     

Hypothalamic knife-cut hyperphagia and obesity in weanling rats

In previous reports weanling female rats fed a high-fat diet had a delayed response to hypothalamic knife cuts. In the present report similar cuts in similar rats fed a standard low fat diet became overweight without delay, suggesting that dietary fat is a critical variable in juvenile onset obesity. Adult rats given knife-cuts comparable to those in the weanlings gained weight far more rapidly and achieved higher weights than did those cut as weanlings, suggesting that appetite modulating axons can develop after weaning. Finally, group vs single housing did not influence the age of onset or the magnitude of knife-cut obesity.     

Menstrual cycle and appetite control: implications for weight regulation

Hormonal fluctuations associated with the menstrual cycle influence appetite control and eating behaviour. Energy intake varies during the reproductive cycle in humans and animals, with a periovulatory nadir and a luteal phase peak. Patterns of macronutrient selection show less consistency but a number of studies report carbohydrate cravings in the premenstrual phase, particularly in women with premenstrual syndrome. The cyclical nature of food cravings are frequently, but not invariably, associated with depression. Fluctuations in appetite, cravings and energy intake during the menstrual cycle may occur in parallel with cyclical rhythms in serotonin, which can be accompanied by affective symptoms. The premenstrual phase can be considered as a time when women are especially vulnerable to overconsumption, food craving and depression; this is often associated with low serotonin activity.      

Sleep related breathing disorders in older men: A search for underlying mechanisms

—The incidence of sleep-related breathing disorders (SRBDs) associated with hemoglobin desaturation was determined by nocturnal polygraphic evaluations in 26 healthy men, aged 55–70 years. Sixteen subjects (62%) had abnormal rates of at least 12 episodes per hour of sleep: 8 had occlusive, and 8 had central apnea or hypopnea. During waking ten of 16 SRBD subjects and only one subject without SRBDs exhibited either an elevated nasopharyngeal airway resistance (n=4) or a reduced ventilatory response to hypercapnia (n=4) and/or hypoxia (n=3). However, these abnormalities were not related to the type or severity of SRBDs, and 6 subjects with SRBDs demonstrated no respiratory defect. We conclude that SRBDs have a very high incidence in older males and are not usually secondary to pulmonary cardiac, neurological, or behavioral disorders. Additionally, we hypothesize that abnormalities in ventilatory control or upper airway resistance contribute to SRBDs, but depression of brain stem reticular formation activity during sleep plays a primary role in these disorders. Factors related to both aging and SRBDs are reviewed. These include reduced chemoreceptor responses, altered steroid hormone metabolism, and use and metabolism of hypnotic drugs and alcohol.     

Expression of superoxide dismutase and xanthine oxidase in myometrium, fetal membranes and placenta during normal human pregnancy and parturition

Superoxide, an agent which attenuates the half-life of nitric oxide, is metabolized and synthesized by superoxide dismutase (SOD) and xanthine oxidase, respectively. Over the last few years much work has focused on the role of nitric oxide in human parturition. The aim of this study was to determine whether the onset of human parturition is associated with a change in the expression of copper/zinc superoxide dismutase (Cu/Zn SOD), manganese superoxide dismutase (Mn SOD) or xanthine oxidase within the uterus. Samples of myometrium, placenta, decidua and fetal membranes were obtained from women before and after the onset of labour at term. Immunocytochemistry was used to localize Cu/Zn SOD, Mn SOD and xanthine oxidase and measure SOD enzyme activity. Cu/Zn and Mn SOD-like immunoreactivity was detected in syncytiotrophoblast cells, villous stromal cells and endothelial cells of blood vessels in the placenta. In the myometrium Cu/Zn and Mn SOD were localized to myocytes and endothelial cells and to some vascular smooth muscle cells. In the fetal membranes we observed staining for Cu/Zn SOD and Mn SOD in the amnion, chorion, extravillous trophoblast and decidua. There was no difference in SOD enzyme activity or staining intensity for SOD between different cell types before and during labour. Xanthine oxidase immunoreactivity was identified in each of the tissues examined and again there was no difference in immunostaining in tissues obtained from women delivered before or after the onset of labour. These results show that the pregnant uterus is capable of both synthesizing and degrading superoxide and suggest that superoxide dismutase and xanthine oxidase may play a role in the maintenance of uterine quiescence during pregnancy, but not in the initiation of parturition.