Immunogenetic considerations in islet transplantation: The role of Ia antigens in graft rejection

As demonstrated by Faustman et al., islets that are pretreated with Ia antibodies and complement show markedly prolonged survival as compared with islets, with the same immunogenetic disparity, without antibody pretreatment. In order to test whether it is simply the absence of an allo-Ia disparity that accounts for this finding, we have transplanted islets across class I disparities alone; in certain cases, such islets are rapidly rejected. Yet, even though there is no allo-Ia difference on such islets, pretreatment of the islets with anti-Ia monoclonal antibody also results in markedly prolonged survival. We suggest that the presence of Ia antigens may serve as a differentiation marker for cells that can present class I antigens in an immunogenic manner; further, allo-Ia antigens can lead to a stronger anti-class I rejection response.     

Partial seizures with focal epileptogenic electroencephalographic patterns in three related female patients with fragile-X syndrome

Epilepsy and abnormal electroencephalographic (EEG) patterns have been reported in mentally retarded males with fragile-X syndrome, but the high incidence of epilepsy in such persons has been recognized only recently. These individuals have focal spikes in the EEG similar to the benign rolandic pattern. Female carriers have very rarely been reported to have epilepsy or nonspecific abnormal EEG patterns. We report partial seizures with a focal epileptogenic EEG pattern in two sisters and their grandmother, who are all carriers of fragile-X syndrome. The sisters have mild developmental delay, but the grandmother is of normal intelligence. The mother of the two sisters is known to be a carrier of the fragile-X chromosome and is of normal intelligence, with no history of seizures. It is important for physicians to be aware of the possibility that females presenting with partial seizures of unknown cause may be fragile-X carriers, and enquiry for a family history of intellectual disability should be pursued.     

Clean Intermittent Catheterization in Boys Using the Lofric Catheter

Purpose

We compared a recently developed hydrophilic catheter to the standard polyethylene catheter in regard to hematuria, infection and patient satisfaction.

Materials and Methods

A hydrophilic LoFric^* or standard Mentor^† catheter was assigned at random to 17 and 16 boys, respectively, who were skilled in intermittent self-catheterization. They were evaluated by weekly urinalysis and a questionnaire.

Results

Significantly fewer episodes of microscopic hematuria occurred in the LoFric than Mentor catheter group (9 episodes in 6 subjects versus 19 episodes in 11, p less than 0.05). There were also fewer episodes of bacteriuria in the LoFric group but the difference was not statistically significant. Mean scores plus or minus standard deviation on a visual analogue scale with 0 equal to most and 10 equal to least favorable were LoFric 3.3 plus/minus 2.8 versus Mentor 4.9 plus/minus 2.7 for catheter convenience and 2.7 plus/minus 2.4 versus 4.2 plus/minus 2.6 for insertion comfort, significantly favoring the LoFric group (p less than 0.05 for both). Of the 16 LoFric subjects 13 preferred to continue its use, particularly those with a history of urethral trauma or sphincteric spasm.

Conclusions

In boys the LoFric catheter appears to cause less trauma. Although it is not reusable and is more expensive than the standard catheter, satisfaction is higher with the LoFric device and for select patients it has significant advantages.     

Cell proliferation kinetics of MCF-7 human mammary carcinoma cells in culture and effects of tamoxifen on exponentially growing and plateau-phase cells

MCF-7 human mammary carcinoma cells were inoculated into 150-sq cm flasks at 3 X 10(5) cells/flask, and after a lag period of about 48 hr, these cells grew exponentially for 5 days with a mean population doubling time of about 24 hr. During exponential growth, 80 to 90% of cells were in the "rapidly cycling" pool, the clonogenic fraction was 50 to 60%, and the mean percentage of cells in the G0-G1, S, and G2 + M phases of the cell cycle was 48.9 +/- 0.6% (S.E.), 39.4 +/- 0.6%, and 11.6 +/- 0.3%, respectively. These parameters changed rapidly between Days 7 and 13 when plateau phase was reached. Between Days 13 and 18, 74.8 +/- 0.7% of cells were in G0-G1, 15.3 +/- 0.4% were in S, and 9.8 +/- 0.6% were in G2 + M phase. Only about 30% of these cells were cycling rapidly, and the clonogenic fraction had fallen to less than 10%. Tamoxifen induced a dose-dependent decrease in the growth rate of exponentially growing cells, which was accompanied by a dose-dependent increase in percentage of G0-G1-phase cells, and a decline in percentage of S-phase cells. At doses greater than or equal to 10 microM, a 24-hr pulse of tamoxifen was cytotoxic to exponentially growing cells. Plateau-phase cells were less sensitive to these effects of tamoxifen. In an attempt to define the kinetic basis of the G0-G1 accumulation induced by tamoxifen, asynchronous MCF-7 cells were pretreated for 42 hr with various doses of tamoxifen, and the rate of efflux of cells from the G0-G1 phase of the cell cycle was assessed by blocking their reentry into G1 with ICRF 159. Following treatment of control cultures with ICRF 159, two populations of cells were distinguished by their rates of efflux from G0-G1 phase. The majority of cells left G0-G1 rapidly with a mean t1/2 of 2.3 hr ("rapidly cycling" cells). However, about 18% of cells had a much slower rate of exit with a mean t1/2 of about 30 hr ("slowly cycling" cells). Pretreatment with tamoxifen resulted in a dose-dependent decrease in the proportion of rapidly cycling cells and an increase in the proportion of cells with slow G1 transit times. Although this appeared to be the predominant effect, tamoxifen also decreased the rate at which the slowly cycling cells traversed G1. Simultaneous treatment with estradiol returned these parameters to control values at doses of tamoxifen less than or equal to 5 microM, partially reversed the effect of 7.5 microM tamoxifen, but was without effect on the arrest of cell cycle progression induced by 10 microM tamoxifen. It is concluded that cells accumulate in G0-G1 following tamoxifen treatment due to an increase in the proportion of slowly cycling cells at the expense of a population of rapidly cycling cells, which appear to be relatively uninfluenced by the drug.     

The ranges of insulin response and glucose tolerance in lean, normal, and obese women during pregnancy.

OBJECTIVE: We characterized insulin secretion and glucose disposal in a large unselected group of women, encompassing the full spectrum of glucose tolerance in pregnancy, and related the findings to maternal obesity. STUDY DESIGN: Intravenous glucose tolerance and first-phase insulin response were measured at about 32 weeks' gestation in 690 unselected pregnancies. The women were designated as "lean," "normal," or "obese" on weight-for-height criteria. RESULTS: The distribution of insulin response was bimodal, but there was no corresponding dichotomy in maternal glucose disposal rate. Insulin response was greatest and glucose disposal rate slowest in obese women. In general, "poor" glucose tolerance was associated with relatively low insulin output. It was not possible to identify any cluster of women, obese or otherwise, in whom poor glucose tolerance was specifically associated with an unusually high insulin response. CONCLUSION: The data indicate that the distribution of glucose tolerance in pregnancy is a continuum. Glucose intolerance represents one end of that spectrum and is attributable to insufficient insulin secretion. This relative insufficiency is most frequent with maternal obesity.     

Effect of nonmedical factors on family physicians' decisions about referral for consultation.

OBJECTIVES: To identify nonmedical factors perceived by family physicians (FPs) and consultants as important influences on decisions about referral for consultation, to determine the relative frequency with which such factors are cited and to identify those factors ranked as most important by the FPs and consultants. DESIGN: Survey with semistructured interview between July 1989 and April 1990. PARTICIPANTS: A total of 41 FPs and 20 consultants who were practising or had practised previously in Nova Scotia. INTERVENTIONS: The questionnaire comprised 10 questions: 4 were nondirective "probes" designed to elicit responses without suggesting possible answers, 2 asked the participants to rank such responses in order of importance, and 4 were "prompts" that asked for comments about a list of factors based on a review of the literature. RESULTS: A total of 4845 discrete items were mentioned as being capable of influencing FPs' decisions about referral for consultation. Aggregation of related items resulted in a list of 35 nonmedical factors, of which 11 were identified by at least half the respondents and 14 by less than half but more than 10. These 25 factors fell into three categories: patient and family factors (e.g., patient's wishes), FP and consultant factors (e.g., FP's capabilities), and other influences (e.g., style of practice). On the basis of both frequency of identification and priority scores "patient's wishes" emerged as the most important factor. Two medical factors that were consistently cited--type of problem and age of patient--were thought to interact with the other factors. CONCLUSION: Certain nonmedical considerations may substantially affect physicians' referral practices.     

Sensory nerve pathology in amyotrophic lateral sclerosis

Summary A detailed morphometric study was performed on sural nerve biopsies to determine the consistency of sensory nerve pathology in amyotrophic lateral slcerosis (ALS) and to seek a correlation between the severity of peripheral nerve pathology and disease duration. Nerve biopsies from patients with ALS consistently showed evidence of early axonal atrophy, increased remylination and a shift in the diameter distributions curve towards smaller fiber diameters. Importantly, the severity of sensory nerve pathlogy in ALS patients correlated with disease duration. The peripheral nerve sodium pump concentration of patients was not reduced. It is concluded that an ingravescent dorsal root ganglion neuronopathy is seen in the incipient stages of ALS, preferentially affecting the largest neurons and resulting in turn in progressive axonal atrophy, secondary demyelination-remyelination and finally in nerve fiber degeneration. Etiologically, a parallel involvement of motor and sensory neurons suggests a more widespread metabolic disturbance in ALS than simply sick motor neurons.Supported by a grant from the New Zealand Neurological Foundation