D2-like dopamine receptor density in Tourette syndrome measured by PET

Tourette syndrome (TS) is a chronic neurologic disorder characterized by the presence of involuntary motor and phonic tics. There is evidence that TS is associated with an abnormality of the dopaminergic system, involving postsynaptic D2 receptors. We tested the hypothesis that D2-like dopamine receptors are elevated in TS.

METHODS

Twenty-nine adult patients with TS were studied by PET imaging with [11C]3-N-methylspiperone ([11C]NMSP). Two methods of data analysis were used. The first was a caudate-to-cerebellar ratio, measured at 45 min. The second method, applied in 20 subjects, was a two-PET scan procedure. Both used high specific activity [11C]NMSP, but the second scan was preceded by a dose of unlabeled haloperidol, which partially occupied the D2-like dopamine receptors. This was done to provide an absolute measure of receptor density (Bmax). All patients were compared to age- and sex-matched controls.

RESULTS

Neither group showed significant differences from their control group in caudate-to-cerebellar ratio. However, the two-PET scan Bmax measurement demonstrated that 4 of the 20 patients had significantly elevated D2-like receptors. In this group of 20 patients, multiple linear regression analysis revealed a trend between the severity of vocal tics and Bmax values. This Bmax measure also revealed a significant (p < 0.05) association with performance on the Wisconsin Card Sorting Test.

CONCLUSION

These findings suggest that not all patients with TS have an abnormality of D2-like receptors, but a subgroup of TS subjects has a significant D2-like dopamine receptor elevation. These findings also support the importance of applying a more quantitative method for Bmax determination to PET imaging analysis. The Bmax findings in the subgroup do not exclude an effect of intrasynaptic dopamine competition, but this effect may be less likely due to the high affinity of [11C]NMSP.

Zinc metabolism in non-insulin dependent diabetes mellitus

Low plasma zinc concentrations and increased zinc excretion have been reported in patients with non-insulin dependent diabetes mellitus (NIDDM). This study was designed to compare zinc metabolism in ten NIDDM patients with ten healthy controls, using stable isotopes of zinc. Zinc absorption from a standard breakfast labelled extrinsically with 3 mg 67Zn was measured using a fecal monitoring technique and thermal ionization quadrupole mass spectrometry. One hour after the test meal each volunteer was given 0.5 mg 70Zn (as citrate) intravenously and blood samples taken at intervals for up to 6 days. Isotopic enrichment was measured and the data entered into a simple kinetic model to estimate the size and rate of turnover of exchangeable pools of zinc. Urinary zinc excretion was higher in the male diabetics than controls (p < 0.05), but not in females. Since the efficiency of absorption and endogenous losses of zinc were very variable between individuals, and there was only a limited amount of data, it was not possible to draw conclusion about the effect of NIDDM on zinc absorption and excretion. However, the fact that there were no differences in exchangeable zinc pool sizes suggests that zinc metabolism is not altered in NIDDM.

Expression of CFTR in human and bovine thyroid epithelium

The expression of cystic fibrosis transmembrane conductance regulator (CFTR) in the thyroid has not been documented to date, although a role for CFTR in the thyroid follicular epithelium is suggested both clinically, by the occurrence of subclinical hypothyroidism in patients with cystic fibrosis (CF), and physiologically, by the presence of low-conductance, adenosine 3',5'-cyclic monophosphate-activated Cl channels in the follicular cells. Using reverse transcriptase-polymerase chain reaction with nested primers derived from exons 13 and 14 of the human CF gene, we have now documented the presence of CFTR mRNA in the human thyroid. Western blot analyses using six antibodies directed against different domains of human CFTR showed that a 165-kDa band was present in membrane extracts from bovine and human thyroid. This protein has the predicted size of mature CFTR and was not detected with preimmune serum or preadsorbed antiserum. By immunofluorescence and immunoperoxidase, CFTR was located in the follicular cells, with a diffuse, intracellular labeling pattern. Quantitative analysis revealed that 64% of the follicles were CFTR positive, but only 16% of the follicular cells were stained per follicle. The number of CFTR-positive cells was inversely proportional to the size of the follicle. These results 1) demonstrate the expression of CFTR at the mRNA and protein levels in human and bovine thyroid follicular cells and 2) suggest that CFTR expression could be instrumental in follicular enlargement.

Epithelial cell polarity and disease

The establishment and maintenance of epithelial polarity is essential for the integrity and function of epithelial organs and is particularly critical in the kidney, where vectorial reabsorption and secretion are effected in different segments of the nephron by the differential polarized insertion of channels, transporters, and related proteins into apical membranes lining the tubule lumen or basolateral membranes adjacent to the interstitium and blood space. Faulty intracellular delivery and polarization of membrane proteins can lead to serious diseases such as cystic fibrosis, I cell disease, and renal cystic diseases. The best understood disease of epithelial polarity is autosomal dominant polycystic kidney disease (ADPKD) caused by mutations in a >462-kDa, developmentally regulated membrane protein, "polycystin." ADPKD cysts are characteristically lined by a single layer of structurally polarized epithelial cells with normal functional intercellular tight junctions but with aberrant polarization of some important membrane proteins. Abnormal apical membrane polarity of biochemically active, ouabain-sensitive Na-K-adenosinetriphosphatase (Na-K-ATPase) in ADPKD cyst epithelia leads to abnormal sodium ion secretion and provides a mechanism for aberrant fluid secretion. In addition, apically mislocated, functional epidermal growth factor (EGF) receptors on cyst epithelia, together with EGF synthesis and secretion into cyst lumens, provide a mechanism for autocrine regulation of increased epithelial cell proliferation in ADPKD. Underlying mechanisms for these abnormalities in polarized distribution of membrane proteins include the aberrant expression of fetal gene products, such as the beta2-subunit of Na-K-ATPase, in ADPKD kidneys. Overexpression of polycystin protein in ADPKD cyst epithelia, low levels restricted to medullary collecting tubules in normal adult kidneys, and high levels in ureteric bud-derived structures in human fetal kidneys further suggest a failure of downregulation of fetal genes as a mechanism for the polarity abnormalities that characterize ADPKD.

Glomerular ultrastructural findings similar to hereditary nephritis in 4 English cocker spaniels

Renal disease affecting 3 male and 1 female English Cocker Spaniels was studied. Clinical features of the disease included proteinuria and progressive deterioration of renal function. Dogs were 11 to 27 months old when euthanized because of severe chronic renal failure. Grossly, the renal cortices were thin. Light microscopic evaluation revealed diffuse glomerular disease characterized by mesangial thickening, glomerular fibrosis, periglomerular fibrosis, and glomerular obsolescence. Based on these clinical and pathologic features, familial nephropathy of English Cocker Spaniels was suspected despite the fact that the individual dogs were not closely related. On transmission electron microscopy, a distinctive ultrastructural lesion was observed in the glomerular basement membranes (GBM) of all dogs. The GBM exhibited extensive thickening, multilaminar splitting, and fragmentation. Electron dense deposits, suggestive of immunocomplex glomerular disease, were notably absent. A similar ultrastructural GBM lesion is found in human beings and Samoyeds with hereditary nephritis, diseases caused by mutations in the type IV collagen genes. Familial nephropathy in English Cocker Spaniels may be a form of hereditary nephritis caused by a mutation in one of the collagen IV genes.

Quantification of neuroreceptors in the living human brain: III. D2-like dopamine receptors: theory, validation, and changes during normal aging

Dopamine receptor density is believed to decline in normal aging. To test this hypothesis, we measured the density of dopamine D2-like receptors in vivo in the neostriatum of normal living humans by using the graphical method. This method determines the D2-like dopamine receptor density in the human brain with an occupying ligand (unlabeled haloperidol) and a radioligand (labeled 3-N-methylspiperone). The method was examined critically, and the assumptions underlying the method were shown to be valid. The validation included comparison of the representation of tracer metabolism by high-pressure liquid chromatography and model assays, calculation of the lumped constant Dw from the value of its components, and comparable tracer partition coefficients in vitro and in vivo. In error analysis, the method consistently performed as well as the direct least-squares regression at statistical noise levels appropriate for the tomograph used in these studies. The method revealed that the density of the D2-like receptors that bind haloperidol in the caudate nucleus of normal humans declined 1% per year after the age of 18 years.

Functional defects in lysosomal enzymes in autosomal dominant polycystic kidney disease (ADPKD): abnormalities in synthesis, molecular processing, polarity, and secretion

The phenotype of autosomal dominant polycystic kidney disease (ADPKD) is characterized by basement membrane abnormalities, hyperproliferation, and alterations in epithelial cell polarity. Since proteinases have been implicated in matrix degradation and growth factor activation, lysosomal enzymes were compared in normal and ADPKD tissues and cell cultures. Acidic proteolytic activity (azocasein) was reduced in ADPKD, and specific enzymatic assays detected disease-dependent decreases in the specific activities of beta-galactosidase, beta-hexosaminidase, and cathepsins, B, L, and H. Cathepsin D-specific activities were unchanged. Lucifer yellow fluorescence in ADPKD cells was consistent with an alteration in heterogeneity of lysosomal enzyme content in ADPKD rather than a decrease in total lysosomal number. Western analysis, metabolic labeling, and immunoprecipitation analysis confirmed decreases in the expression and synthesis of the major normal molecular immunoreactive species of beta-galactosidase and cathepsins B and H in ADPKD tissue and cells but no changes in cathepsin D. In addition, ADPKD-specific high-molecular-weight species of cathepsin H were seen and abnormal forms of cathepsin B and beta-galactosidase were common in ADPKD, suggesting abnormal molecular processing and posttranslational modifications. In addition, immunolocalization studies showed abnormal apical plasma-membrane localization of cathepsins B and H in ADPKD cyst epithelial cells, consistent with a protein sorting defect in ADPKD. Increased extracellular secretion of lysosomal enzymes was also measured in ADPKD cultured cells and in filter-grown epithelia shown to be predominantly directed to the basal compartment. These results demonstrate that lysosomal enzyme alterations in ADPKD may play a role in aberrant processing of the basement membrane. Alterations in the polarized secretion of lysosomal enzymes by ADPKD epithelia in vitro were also detected. Whereas all normal epithelia cells secreted lysosomal enzymes predominantly to the apical medium compartments, basally directed secretion was increased in all ADPKD epithelia and attained an overall reversal of polarity for cathepsins B + L. It is concluded that alterations in lysosomal enzyme function in ADPKD are the result of alterations in synthesis, molecular processing, and polarized secretion of specific enzymes and may have impact on proliferative and basement membrane abnormalities in this genetic disease. These results are consistent with a fundamental defect in protein processing sorting, and trafficking in ADPKD.

Developmental regulation of CFTR expression during human nephrogenesis

Cystic fibrosis transmembrane conductance regulator (CFTR) mRNA and protein are expressed in proximal and distal tubules of the human kidney, but CFTR expression pattern during human nephrogenesis is unknown. We have now studied CFTR expression in fetal kidneys by immunohistochemistry and Western blot analysis, using six antibodies against human CFTR. CFTR was expressed in 12-wk human fetal kidneys, mostly in the apical membrane region of the ureteric bud epithelial cells. By 15 wk, CFTR was also diffusely expressed throughout the cytoplasm of proximal tubules and loops of Henle. No glomerular staining was seen at any state. From 15 to 24 wk of gestation this staining pattern remained constant and also included immunoreactivity of the transitional epithelium. Western blot for CFTR was performed on membrane extracts of human fetal kidneys, using T84 cells as a positive control. A 165-kDa protein corresponding to the predicted size of CFTR was seen at 13 wk and throughout development. We also observed a 75-kDa protein that was distinctly regulated during development. This protein was detected with several antibodies against the first half of CFTR (including the regulatory "R" domain) but not with a COOH-terminal-specific antibody and had the predicted size of a functional splice variant of CFTR identified in the human kidney. These results show the complex regulation of CFTR during nephrogenesis and raise the question of the respective roles of the full-length and the splice variant CFTR proteins in the human kidney.

A retrospective analysis of the effect of antenatal steroid administration on the incidence of respiratory distress syndrome in preterm twin pregnancies

Respiratory distress syndrome (RDS) is the major cause of morbidity and mortality in preterm twin deliveries. Therapy with corticosteroids has been shown to reduce the incidence of RDS in preterm singleton gestations but similar reductions in twin pregnancies have not been demonstrated. Maternal and neonatal medical records were reviewed from twins delivered between 24 to 34 weeks gestation over the period of January 1, 1990 to December 31, 1994. Twenty-one pairs of twins received optimal steroid treatment defined as the use of two 12 mg doses of betamethasone, with birth occurring between 24 hours and 7 days after the first dose. Sixty-three pairs received no treatment. The mean gestational age at delivery was 29.9 +/- 2.6 weeks. No decrease was seen in the incidence of RDS (optimal steroid 70.7% versus no treatment 68.0%, unadjusted odds ratio [OR] 1.14, 95% confidence interval [CI] 0.49 to 2.65). Multivariate logistic regression showed no statistical difference in the incidence of RDS in the optimal steroid compared to the no treatment group (adjusted OR 0.63, 95% CI 0.2 to 1.95). No statistical differences were noted in the incidence of mechanical ventilation (58.6% versus 55.4%, p = 0.83), median duration of intubation (5.0 versus 5.0 days, p = 0.47), the median maximum inspiratory pressure requirements (20.0 versus 22.0 mm Hg; p = 0.15) in the optimal treatment versus no treatment group, respectively. The current regimen of antenatal corticosteroids utilized in twin pregnancies does not reduce the incidence of RDS.

Expression of aquaporins-1 and -2 during nephrogenesis and in autosomal dominant polycystic kidney disease

Aquaporin-1 (AQP1), located in proximal tubules (PT) and descending thin limbs of Henle (DTL), and aquaporin-2 (AQP2), located in collecting ducts (CD), are channels involved in water transport across renal tubule epithelia. Using antibodies against AQP1 and AQP2, we here show expression of AQP1 and AQP2 in normal human developing and adult kidneys and in autosomal dominant polycystic kidney disease (ADPKD). Unlike in rats, AQP1 and AQP2 are expressed early during human nephrogenesis (12-wk gestation). AQP1 was first seen in developing PT epithelia, predominantly in apical cell membranes, and, at 15 wk, was also detected in DTL. AQP2 was seen in apical cell membranes of the branching ureteric bud and CD system from 12 wk and throughout development. In adult normal kidneys, AQP1 was localized to apical and basolateral membrane domains of PT and DTL, whereas AQP2 was restricted to principal cells of CD. This distribution of AQP1 and AQP2 was also seen in early stage ADPKD, except that AQP1 was mostly located in the apical membrane region of expanded PT. In end-stage ADPKD, two-thirds of the cysts expressed either AQP1 or AQP2, but these two water channels were never colocalized in the same cyst. Western blot analysis showed maximal expression of AQP1 and AQP2 in normal adult kidneys, lower levels in fetal kidneys, and decreases associated with degree of cystic progression in ADPKD. These data 1) demonstrate specific, mutually exclusive localization of AQP1 and AQP2 in human fetal and adult kidneys; 2) show that both channels are expressed early during nephrogenesis; and 3) show that the mutual exclusivity of localization is maintained even into end-stage ADPKD.

Both the wild type and a functional isoform of CFTR are expressed in kidney

The cystic fibrosis transmembrane conductance regulator (CFTR) consists of five domains, two transmembrane-spanning domains, each composed of six transmembrane segments, a regulatory domain, and two nucleotide-binding domains (NBDs). CFTR is expressed in kidney, but its role in overall renal function is not well understood, because mutations in CFTR found in patients with cystic fibrosis are not associated with renal dysfunction. To learn more about the distribution and functional forms of CFTR in kidney, we used a combination of molecular, cell biological, and electrophysiological approaches. These include an evaluation of CFTR mRNA and protein expression, as well as both two-electrode and patch clamping of CFTR expressed either in Xenopus oocytes or mammalian cells. In addition to wild-type CFTR mRNA, an alternate form containing only the first transmembrane domain (TMD), the first NBD, and the regulatory domain (TNR-CFTR) is expressed in kidney. Although missing the second set of TMDs and the second NBD, when expressed in Xenopus oocytes, TNR-CFTR has cAMP-dependent protein kinase A (PKA)-stimulated single Cl- channel characteristics and regulation of PKA activation of outwardly rectifying Cl- channels that are very similar to those of wild-type CFTR. TNR-CFTR mRNA is produced by an unusual mRNA processing mechanism and is expressed in a tissue-specific manner primarily in renal medulla.

Obstetric practice and the prevalence of urinary incontinence three months after delivery

OBJECTIVE

To examine the relation between obstetric factors and the prevalence of urinary incontinence three months after delivery.

DESIGN

2134 postal questionnaires sent between August 1989 and June 1991.

SETTING

Teaching hospital in Dunedin, New Zealand.

SUBJECTS

All women three months postpartum who were resident in the Dunedin area.

MAIN OUTCOME MEASURE

Prevalence of urinary incontinence.

RESULTS

1505 questionnaires were returned (70.5% response rate). At three months postpartum 34.3% of women admitted to some degree of urinary incontinence with 3.3% having daily or more frequent leakage. There was a significant reduction in the prevalence of incontinence for women having a caesarean section, in particular in primiparous women with a history of no previous incontinence (prevalence of incontinence following a vaginal delivery 24.5%, following a caesarean section 5.2% P = 0.002). There was little difference between elective caesarean sections and those carried out in the first and second stages of labour. The odds ratios for women having a caesarean section were 0.4 (95% confidence interval (CI) 0.2.-0.7) (all women and all primiparae) and 0.2 (95% CI 0.0-0.6) (primipara with no previous incontinence) in comparison with those having a normal vaginal delivery. The prevalence of incontinence was also significantly lower in women having had two caesarean sections (23.3%; P = 0.05) but similar in those women having three or more caesarean sections (38.9%) in comparison with those women who delivered vaginally (37.7%). Other significant independent odds rations were found for daily antenatal pelvic floor exercises (PFE) (0.6, 95% CI 0.4-0.9), parity > or = 5 (2.2, 95% CI 1.0-4.9) and pre-pregnancy body mass index (1.07, 95% CI 1.04-1.10).

CONCLUSIONS

Adverse risk factors for urinary incontinence at three months postpartum are vaginal delivery, obesity and multiparity (> or = 5). Caesarean section and daily antenatal PFE appear to be protective, although not completely so.

NHE2 and NHE3 are human and rabbit intestinal brush-border proteins

Rabbit NHE2 and NHE3 are two epithelial isoform Na+/H+ exchangers (NHE), the messages for which are found predominantly and entirely, respectively, in renal, intestinal, and gastric mucosa. The current studies used Western analysis and immunohistochemistry to identify and characterize the apical vs. basolateral membrane distribution of NHE2 and NHE3 in intestinal epithelial cells. Based on Western analysis, NHE2 and NHE3 both are present in brush-border but not basolateral membranes of small intestine. Both NHE2 and NHE3 are 85-kDa proteins. Consistent with Western analysis, NHE2 and NHE3 are immunolocalired to the brush-border but not basolateral membranes of villus epithelial cells, but not goblet cells, in human jejunum and ileum and in surface epithelial cells in the ascending and descending colon and rectum. In addition, NHE2 and NHE3 are present in small amounts in the crypt cell brush border of human jejunum, ileum, ascending and descending colon, and rectum. In rabbit jejunum, ileum, and ascending colon, NHE2 and NHE3 are present in the brush border of epithelial and not goblet cells, again much more in the villus (small intestine)/ surface cells (colon) than the crypt. NHE2 but not NHE3 is present in the brush border of rabbit descending colon surface cells and in small amounts in crypt cells. NHE2 and NHE3 are both human and rabbit small intestinal and colonic epithelial cell brush-border Na+/H+ exchanger isoforms that colocalize in all intestinal segments except rabbit descending colon, which lacks NHE3.

A role for CFTR in human autosomal dominant polycystic kidney disease

Human autosomal dominant polycystic kidney disease (ADPKD) is the most common lethal dominant hereditary disorder characterized by enormous renal enlargement and the development of multiple cysts originating from nephrons. We investigated the pathogenesis of cyst formation in ADPKD by using patch-clamp and immunocytochemical techniques. Adenosine 3',5'-cyclic monophosphate-activated Cl- currents are present in primary cultures of ADPKD cells and have characteristics such as a linear current-voltage relation, insensitivity to 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid, sensitivity to glibenclamide and diphenylamine carboxylic acid, and an anion selectivity sequence of Br- > Cl- > I- > glutamate, all of which are identical to cystic fibrosis transmembrane conductance regulator (CFTR). With the use of CFTR antibodies raised against the regulatory and first nucleotide-binding domains, CFTR was detected in primary cultures of ADPKD cells. Similar results were obtained in vivo in cyst-lining epithelial cells in ADPKD kidneys, where staining was seen associated with the apical membrane regions. These data indicate that the CFTR Cl- channel exists in apical membranes of ADPKD cells and may play an important role in cyst formation or enlargement.

Renal proximal tubular epithelium from patients with nephropathic cystinosis: immortalized cell lines as in vitro model systems

The renal proximal tubule is a major site of injury in a variety of congenital/metabolic diseases including nephropathic cystinosis, the most commonly known cause of renal Fanconi's syndrome. In this lysosomal storage disease there are defects in proximal tubule function within the first few months of life. While culture of renal tubular cells from the urine of these patients is possible, development of immortalized cell lines would insure large numbers of homogeneous cells for studies of renal epithelial cell morphology and pathophysiology in this disease. To develop immortalized cells, cystinotic and normal proximal tubular cells in culture were exposed to an immortalizing vector, containing pZiptsU19 with the temperature sensitive SV40 T-antigen allele tsA58U19 and a neomycin resistance gene, and neomycin-resistant tubular cells were selected for propagation. Ten clones from cystinotic patients have been developed and characterized. All clones express T-antigen at permissive temperature (33 degrees C). Immortalized cells have an epithelial morphology and grow to form confluent monolayers; doubling times vary from 31 to 86 hours. Cystinotic clones are keratin, MDR P-glycoprotein, and alpha-95 kD brush-border associated protein positive but Tamm-Horsfall protein negative by immunocytochemistry, as are normal proximal tubule cells immortalized with this vector. This is consistent with a proximal tubule origin of the cystinotic clones. The cystine content of the cystinotic cells is 70 to 160 times that of normal renal proximal tubular cells in culture, with most of the cystine sequestered in cell lysosomes, confirming that these cell lines express the storage defect.(ABSTRACT TRUNCATED AT 250 WORDS)

Growth and the uptake of sucrose and mineral ions by transformed root cultures of Datura stramonium, Datura Candida x aurea, Datura wrightii, Hyoscyamus muticus and Atropa belladonna

Growth and the uptake of sucrose, anions (Cl(-), NO3(-), PO4(3-), and SO4(2-)), and cations (K(+), Na(+), Mg(2+), Ca(2+), and NH4(+)) by transformed roots of Datura stramonium, Datura wrightii. Datura candida x Datura aurea hybrid, Hyoscyamus muticus, and Atropa belladonna were examined during batch culture over 28 days in modified 14 litre stirred tank reactors containing Gamborg's B5 salts medium. All cultures completely removed NH4(+) and PO4(3-) from the medium, and Mg(2+) was totally removed by the Datura cultures. The other ions were consumed at different rates depending on the culture but were never totally removed from the medium. Amounts for each ion consumed per gram increase in biomass are presented and compared between the different cultures. More NO3(-) than any other ion was consumed by each of the cultures. Concomitant with the uptake of sucrose was a slow release of glucose into the medium. Roots were found to contain only low levels of free sugars. Total hyoscyamine production ranged from 115 mg to 633 mg per reactor.

Abnormal polarization of EGF receptors and autocrine stimulation of cyst epithelial growth in human ADPKD

The underlying mechanism of the hyperproliferative response of human autosomal dominant polycystic kidney disease (ADPKD) epithelia was studied. Epidermal growth factor (EGF) protein is highly expressed in ADPKD cyst epithelia in vivo, and primary cultures are hyperesponsive to mitogenic stimulation by EGF in vitro. Doses of > 1 ng/ml EGF were highly mitogenic to ADPKD epithelia. 3H-labeled thymidine proliferation assays showed that cyst fluids and ADPKD epithelial cell-conditioned media also stimulated renal epithelial cell proliferation and contained EGF immunoreactivity (6, 30, and 37 kDa) as detected by Western blots. Radioimmunoassays detected mean levels of 2.87 and 1.4 ng/ml EGF in cyst fluids from early (proliferative) and end-stage ADPKD cysts, respectively. Scatchard analysis of 125I-labeled EGF binding to apical and basolateral membrane showed high-affinity binding to basolateral membranes of normal and ADPKD kidneys but additional unique high-affinity receptor binding to apical membranes of ADPKD but not normal kidneys. Cross-linking analysis and antiphosphotyrosine Western analysis demonstrated functionally active apical EGF receptors at 150-170 kDa. These results suggest mediation of cyst expansion via an autocrine loop involving EGF synthesis and processing by cyst epithelial cells, apical secretion into cyst lumens, and subsequent binding to and phosphorylation of apical membrane EGF receptors. These findings are consistent with a membrane protein polarization defect in ADPKD cyst epithelia.

Autogenous bone grafts from the femoral head for the treatment of acetabular deficiency in primary total hip arthroplasty with cement. Long-term results

Thirty-five consecutive total hip arthroplasties in twenty-eight patients were performed with use of cement and insertion of an autogenous graft from the femoral head. Five patients (six hips) subsequently died or were lost to follow-up. The results for the remaining twenty-three patients (twenty-nine hips) were reviewed retrospectively at a mean of eleven years (range, seven to seventeen years) after the operation. All of the grafts united. The mean estimated coverage of the acetabular component by the autogenous graft was 27 per cent (range, 15 to 45 per cent). Three sockets (10 per cent) were revised because of symptomatic loosening without infection at a mean of ten years (eight, ten, and twelve years) after the index procedure. All three hips were found to have viable, bleeding bone in the region of the remaining graft. An additional eight acetabular components had a nonprogressive, asymptomatic, continuous radiolucent line at the cement-bone interface. This finding was assumed to indicate loosening of the socket, so the total prevalence of loosening was 38 per cent (eleven of twenty-nine sockets). There was no significant difference between the loose and the well fixed components in terms of the amount of coverage by the graft (p > 0.2) or the method of fixation (p > 0.4). There was no collapse or resorption of the graft that was of mechanical consequence. Autogenous femoral-head bone-grafting is a useful technique with a good potential for long-term success when the amount of coverage by the graft is limited to less than 40 per cent of the surface of the acetabular component.

Longitudinal data analysis for linear Gaussian models with random disturbed-highest-derivative-polynomial subject effects

For linear regression analysis of longitudinal data with Gaussian response, I propose a new model to generalize the traditional class of random effects models in which the random effects are deterministic polynomials with coefficients randomly distributed over subjects with mean zero. The generalization is accomplished by adding zero mean Gaussian 'disturbances' to the highest derivative of each random coefficient subject polynomial, independently at each observation time. The resulting random effects, which have mean zero at each observation time, are called disturbed highest derivative polynomials (DHDPs). The disturbances induce serial correlation and also allow the subject-specific DHDP time trends to be non-linear. I do not estimate the subject-specific DHDP time trends. Analysis is based on the marginal model, that is, the fixed effects or population model obtained by integrating the random polynomial coefficients and all disturbances out of the joint distribution of themselves and the response vector. This allows a 'population averaged' interpretation. One can select the DHDP order by an information criterion. When the population time trend is not correctly modelled, the optimal DHDP order will be larger than when it is correctly modelled. One can make the covariance matrix of the regression coefficients robust to errors in modelling the within-subject dependence. I describe the relationship of a DHDP to a smoothing polynomial spline, and show how to replace the DHDP model with a smoothing polynomial spline model for the within-subject dependence in the marginal model.

The validity of extrinsic stable isotopic labeling for mineral absorption studies in rats

The use of extrinsic stable and radioisotopic labels (Fe, Zn, Cu and Se) was compared with the use of intrinsic labels by measuring label retention in rats. Saccharomyces cerevisiae (Hansen strain CBS 1171) was prepared intrinsically enriched with a stable isotope of iron, zinc, copper or selenium, and unenriched freeze-dried yeast was extrinsically labeled with the appropriate stable and/or radioisotope. Male Wistar rats, weighing 80-100 g and fed a purified diet, were given a test meal of one of the above labeled yeasts. Isotopic retention was determined by fecal monitoring. Retention of the stable isotopes was determined by thermal ionization quadruple mass spectrometry (TIQMS) and retention of the radioisotopes by counting feces in a whole-body counter. The results indicated that the behavior of the labels differed among the minerals, with copper as the only one in which the intrinsic and extrinsic stable isotopes were comparably retained. With zinc, retention of the extrinsic radiolabel and intrinsic label was similar, but retention of the extrinsic stable isotope label was higher. With iron, the intrinsic label had a significantly lower retention than the two extrinsic labels; with selenium, retention of all three labels was different, but these differences were not of a sufficient magnitude to conclude that extrinsic stable isotopic labelling is not valid. These results demonstrate that an extrinsic stable isotope label can be used for copper, selenium and inorganic iron, but that such a label is not valid for studies on zinc.

Southland Hospital's experience with the Austin Moore hemiarthroplasty

AIM

The assessment of hospital performance with reference to patients who receive Austin Moore hemiarthroplasty for neck of femur fractures and the assessment of patients at medium term follow up.

METHODS

A retrospective review of 103 Austin Moore hemiarthroplasties in 101 patients. This review spans an 11 year period at this institution. A clinical follow up of survivors including pain, x-ray and Harris hip score to evaluate their current position.

RESULTS

Mean hospital stay remained unchanged at 39.13 days. Also unchanged were the percentage of patients returning home at 44.6%. The time to surgery improved significantly over the review period being on average 2.8 days. Medium term follow up of surviving patients (16 patients) showed 14 patients with poor Harris hip scores. Radiographic analysis did not explain the clinical outcome.

CONCLUSIONS

Whilst at this institution, total time to surgery improved total hospital stay and percentage discharged home remained unchanged. Medium term surviving Austin Moore patients should be followed as their hip function may deteriorate excessively with time. The predicted increase in patient load will further pressure the current resources making substantial improvements more difficult.

Spectrophotometry and organic matter on Iapetus. 1. Composition models

Iapetus shows a greater hemispheric albedo asymmetry than any other body in the solar system. Hapke scattering theory and optical constants measured in the laboratory are used to identify possible compositions for the dark material on the leading hemisphere of Iapetus. The materials considered are poly-HCN, kerogen, Murchison organic residue, Titan tholin, ice tholin, and water ice. Three-component mixtures of these materials are modeled in intraparticle, particle, and areal mixtures. In a computer grid search of approximately 2 x 10(7) models, an intraparticle mixture of 25% poly-HCN, 10% Murchison residue, and 65% water ice is found to best fit the spectrum, albedo, and phase behavior of the dark material. The Murchison residue and/or water ice can be replaced by kerogen and ice tholin, respectively, and still produce very good fits. Areal and particle mixtures of poly-HCN, Titan tholin, and either ice tholin or Murchison residue are also possible models. Poly-HCN is a necessary component in almost all good models. The presence of poly-HCN can be further tested by high-resolution observations near 4.5 micrometers.

Changes in mortality after total hip and knee arthroplasty over a ten-year period

A retrospective review of in-hospital mortality after total hip and total knee arthroplasty was performed to determine whether extensive changes in anesthesia care, introduced in this institution in July 1986, were associated with changes in mortality rates. From 1981 to 1985, the mortality rate was 0.39% (23 of 5874 patients) and from 1987 to 1991, the mortality rate was 0.10% (10 of 9685 patients) (P = 0.0003). Significant reductions in mortality rate were observed for both total hip arthroplasty (from 0.36% to 0.10%) (P = 0.0277) and total knee arthroplasty (from 0.44% to 0.10%) (P = 0.0131). The mortality rate of 0.10% is significantly less than previously published rates. Marked changes in anesthesia management were associated with a significant reduction in mortality after total hip and knee arthroplasty.