Precursors of literacy delay among children at genetic risk of dyslexia

This paper reports the literacy skills of 63 children selected as being at genetic risk of dyslexia compared with 34 children from families reporting no history of reading impairment. Fifty-seven per cent of the at-risk group were delayed in literacy development at 6 years compared with only 12% of controls. The "unimpaired" at-risk group were not statistically different from controls on most cognitive and language measures at 45 months, whereas the literacy-delayed group showed significantly slower speech and language development, although they did not differ from controls in nonverbal ability. Letter knowledge at 45 months was the strongest predictor of literacy level at 6 years. In addition, early speech and language skills predicted individual differences in literacy outcome and genetic risk accounted for unique variance over and above these other factors. The results are discussed in terms of an interactive developmental model in which semantic and phonological skills support early reading acquisition.

Neurotrophin-3 reverses nerve conduction velocity deficits in streptozotocin-diabetic rats

The ability of neurotrophin-3 (NT-3) to reverse established nerve disorders was investigated in the peripheral neuraxis of streptozotocin-diabetic rats. Sciatic sensory and motor nerve conduction velocity deficits established after 2 months of diabetes were completely normalized by one further month of treatment with either NT-3 or insulin. None of these conduction velocity changes were associated with altered mean axonal caliber in the sciatic nerve. In the dorsal and ventral roots, mean axonal caliber was significantly decreased after 8 weeks of diabetes (both P < 0.05). Subsequently, one month of insulin, but not NT-3, treatment increased mean axonal caliber to age-matched control values. NT-3 treatment was also without effect on the significant (both P < 0.05) decrease in phosphorylated heavy neurofilament (NFH) subunits seen in dorsal and ventral roots of 12 week diabetic rats. In the sural nerve, diabetes attenuated a maturation-associated increase in mean axonal caliber over the first 8 weeks of diabetes, and induced atrophy between weeks 8 and 12 that was ameliorated by both NT-3 and insulin treatment. Reductions in sural nerve axonal caliber were associated with a tendency for elevation of both phosphorylated NFH levels in large fibers and the ratio of phosphorylated to nonphosphorylated NFH that was attenuated by NT-3. These data demonstrate that NT-3 corrects established sciatic nerve conduction deficits in diabetic rats in a manner independent of changes in axonal caliber in this nerve. Further, although NT-3 was without effect on decreases in axonal caliber and NFH subunit phosphorylation in the spinal roots, reversal of axonal caliber deficits in peripheral nerves of sensory fibers may involve NT-3-mediated normalization of aberrant neurofilament phosphorylation.

A cultural effect on brain function

We present behavioral and anatomical evidence for a multi-component reading system in which different components are differentially weighted depending on culture-specific demands of orthography. Italian orthography is consistent, enabling reliable conversion of graphemes to phonemes to yield correct pronunciation of the word. English orthography is inconsistent, complicating mapping of letters to word sounds. In behavioral studies, Italian students showed faster word and non-word reading than English students. In two PET studies, Italians showed greater activation in left superior temporal regions associated with phoneme processing. In contrast, English readers showed greater activations, particularly for non-words, in left posterior inferior temporal gyrus and anterior inferior frontal gyrus, areas associated with word retrieval during both reading and naming tasks.

Detection of Epstein-Barr virus (EBV) genomes in the serum of patients with EBV-associated Hodgkin's disease

DNA from malignant cells is present in the serum/plasma of cancer patients and DNA from this source is amenable to analysis by polymerase chain reaction (PCR). In the present study, we evaluated whether Epstein-Barr virus (EBV) DNA is present in the serum of patients with EBV-associated Hodgkin's disease (HD). Using conventional PCR, EBV DNA was detected in serum from 30/33 patients with EBV-associated HD but in only 6/26 patients with non-EBV-associated disease (p < 0.001). Samples from healthy individuals were negative and only 5/12 infectious mononucleosis samples were positive. Real-time quantitative PCR was subsequently employed to determine the concentration of EBV DNA present in serum; among positive samples the level ranged from 1 to 705 copies per 125 microliter of serum. Post-treatment samples from 5/14 cases with EBV-associated HD contained detectable EBV DNA; analysis of this small group of cases suggests that positivity in post-treatment samples correlates with risk factors indicative of a poor prognosis. Overall, our results are consistent with the notion that DNA from Reed-Sternberg cells is present in the serum of HD patients, and further suggest that serum EBV should be evaluated as a prognostic marker. Int. J. Cancer (Pred. Oncol.) 84:442-448, 1999.

Aberrant neurofilament phosphorylation in sensory neurons of rats with diabetic neuropathy

Aberrant neurofilament phosphorylation occurs in many neurodegenerative diseases, and in this study, two animal models of type 1 diabetes--the spontaneously diabetic BB rat and the streptozocin-induced diabetic rat--have been used to determine whether such a phenomenon is involved in the etiology of the symmetrical sensory polyneuropathy commonly associated with diabetes. There was a two- to threefold (P < 0.05) elevation of neurofilament phosphorylation in lumbar dorsal root ganglia (DRG) of diabetic rats that was localized to perikarya of medium to large neurons using immunocytochemistry. Additionally, diabetes enhanced neurofilament M phosphorylation by 2.5-fold (P < 0.001) in sural nerve of BB rats. Neurofilaments are substrates of the mitogen-activated protein kinase (MAPK) family, which includes c-jun NH2-terminal kinase (JNK) or stress-activated protein kinase (SAPK1) and extracellular signal-regulated kinases (ERKs) 1 and 2. Diabetes induced a significant three- to fourfold (P < 0.05) increase in phosphorylation of a 54-kDa isoform of JNK in DRG and sural nerve, and this correlated with elevated c-Jun and neurofilament phosphorylation. In diabetes, ERK phosphorylation was also increased in the DRG, but not in sural nerve. Immunocytochemistry showed that JNK was present in sensory neuron perikarya and axons. Motoneuron perikarya and peroneal nerve of diabetic rats showed no evidence of increased neurofilament phosphorylation and failed to exhibit phosphorylation of JNK. It is hypothesized that in sensory neurons of diabetic rats, aberrant phosphorylation of neurofilament may contribute to the distal sensory axonopathy observed in diabetes.

Home is where the care is

This article describes how a children's home care service operates as part of a general paediatric service within an acute NHS trust. Although a debate exists about whether a home care service should be set up as part of a community or acute trust, there are advantages and drawbacks for staff within either system. The authors believe that children benefit regardless of where the service is based.

The porcine calcitonin receptor promoter directs expression of a linked reporter gene in a tissue and developmental specific manner in transgenic mice

We have investigated the transcriptional regulation of the porcine calcitonin (CT) receptor (pCTR) promoter in transgenic mice. A construct containing 2.1 kb pCTR 5' flanking region, fused to a beta-galactosidase (lacZ) gene, was employed for the production of transgenic mice. At 11.5 days of development lacZ expression was observed in the embryonic brain and spinal cord. By 15.5 days post fertilization, lacZ expression was detected in the developing mammary gland, external ear, cartilage primordium of the humerus, and anterior naris (nostril). RT-PCR on RNA from these fetal tissues showed endogenous mouse CTR (mCTR) expression. In neonatal and adult transgenics, lacZ expression was silenced, except in brain, spinal cord, and testis (adults only). Endogenous mCTR gene expression and pCTR promoter activity were corepressed in the same tissues from adult mice. No pCTR promoter activity was detected in the kidney or bone of transgenic animals. This suggests that additional DNA sequences may be required for pCTR promoter activity in these tissues. From these results, we conclude that the pCTR promoter is active only in tissues expressing endogenous mCTR. Many of the these tissues represent previously unknown sites of CTR gene expression. Finally, the developmental regulation of pCTR/mCTR in tissues such as breast and cartilage primordium suggests that CTRs may play a role in the morphogenesis of these tissues.

Nitric oxide inhibits lipopolysaccharide-induced apoptosis in pulmonary artery endothelial cells

Our group recently reported that cultured sheep pulmonary artery endothelial cells (SPAECs) became resistant to lipopolysaccharide (LPS)-induced apoptosis several days after constitutive synthesis of nitric oxide (NO) after adenoviral (Ad) transfer of inducible NO synthase (iNOS) or exposure to the NO donor S-nitroso-N-acetylpenicillamine (SNAP) (E. Tzeng, Y.-M. Kim, B. R. Pitt, A. Lizonova, I. Kovesdi, and T. R. Billiar. Surgery 122: 255-263, 1997). In the present study, we confirmed this observation by establishing stable transfectants after retroviral gene transfer [replication-deficient retrovirus (DFG)] of human iNOS (DFG-iNOS) SPAECs and then used all three approaches (Ad, DFG, and SNAP) to determine underlying mechanisms of this phenomenon. Continuous endogenous production of NO in itself did not cause apoptosis as assessed by phase-contrast microscopy, nuclear morphology, and internucleosomal DNA fragmentation. Prolonged (72-96 h) synthesis of NO, however, after DFG- or replication-deficient adenovirus (Ad. CMV)-iNOS or SNAP (100 microM, 96 h) inhibited LPS-induced apoptosis. The kinetics of such protection suggested that NO may be inducing other gene products. Ad-mediated transfer of manganese superoxide dismutase (MnSOD) decreased the sensitivity of wild-type SPAECs to LPS-induced apoptosis. MnSOD, however, was not induced in an NG-monomethyl-L-arginine (L-NMMA)-sensitive time-dependent fashion after Ad.CMV-iNOS. Other inducible genes that may be affected by NO and that may protect against potential oxidant-mediated LPS-induced apoptosis including 70-kDa heat shock protein, heme oxygenase-1, metallothionein, and Bcl-2 also were not elevated in an L-NMMA-sensitive, time-dependent fashion. Although the candidate gene product underlying NO-induced protection remains unclear, we did note that prolonged synthesis of NO inhibited LPS-induced activation of an interleukin-1beta-converting enzyme-like cysteine protease (cysteine protease protein-32-like) in a dithiothreitol-sensitive fashion, suggesting that S-nitrosylation of an important downstream target of convergence of apoptotic signals may contribute to the sensitivity of SPAECs to LPS.

Lack of involvement of known oncogenic DNA viruses in Epstein-Barr virus-negative Hodgkin's disease

Epstein-Barr virus (EBV) is associated with around one-third of cases, but young adult cases are rarely EBV associated. In this study, known oncogenic DNA viruses, including human adenoviruses, papovaviruses and the human herpesviruses-6 (HHV-6) and -8 (HHV-8) were not detected in Hodgkin's disease lesions. These results suggest that an as yet unidentified infectious agent is involved in the pathogenesis of non-EBV-associated Hodgkin's disease.

Evaluation of joint medical and nursing notes with preprinted prompts

OBJECTIVE

To determine the views of doctors and nurses about two recent innovations in the structure of case notes: the use of preprinted prompts and the use of joint medical and nursing notes.

DESIGN

Questionnaire survey of all doctors and nurses working on the children's wards.

SETTING

Children's wards in a district general hospital.

MAIN OUTCOME MEASURES

Whether or not respondents wanted to return to traditional notes; positive and negative aspects of the two innovations.

RESULTS

There was an 81% response rate. 45 of 48 respondents (94%) did not want to return to traditional notes. Positive features of joint notes that were identified included: promotes team work (21/48 respondents), improves access to information (14/48), and reduces duplication (14/48). Negative features included uncertainty about identity of writer (8/48) and incompletely filled in sheets (7/48). Positive features of preprinted prompts included: less information omitted (29/48), easier to read and find information (28/48), and quicker to write (21/48). Negative features included: not enough space (19/48) and clerking too mechanical (16/48).

CONCLUSION

Advantages of both innovations outweighed their disadvantages to the extent that only three out of 48 respondents wanted to return to writing traditional notes.

RAS and the myelodysplastic syndromes

RAS genes have been implicated in several different malignancies. The mechanism of activation in most cases has been due to point mutations at critical domains responsible for guanine nucleotide binding. These changes alter the conformation of the protein resulting in insensitivity of the protein to the GTPase activating protein which normally hydrolyses the active p21RAS GTP-bound form to the inactive GDP-bound form. RAS genes have potent effects on the differentiation and proliferation program of cells. The mechanism induced depends on the context in which RAS is found as well as its mutational status and indeed which RAS gene family member is involved. RAS mutations have been described early in the disease process in haematologically normal individuals at risk of mutations induced by either occupational hazard exposure, such as benzene, or of secondary disease after chemotherapy for a previous malignancy. It also been associated with disease progression from myelodysplasia (MDS) to acute myelogenous leukaemia (AML), but it has also been described to be lost upon disease progression, thus showing that RAS mutations are unlikely to be initiating events or at least not required for maintenance of disease. As RAS appears to be involved in primary and secondary myeloid leukaemias, it is a good candidate for gene targeted therapeutic intervention. Studies to target RAS either directly or indirectly by interfering in the RAS pathway are underway. Clinical trials with a peptide RAS vaccine are also ongoing in solid tumours. This report seeks to review the evidence for RAS involvement as oncogenes, focusing on MDS, the reasons as to why the hot spots of codons 12/13 and 61 are particularly potent in activating the transformation potential of RAS and the different approaches being undertaken to translate laboratory findings into therapeutic reality.

Poor Recovery of Surface Orientation from VDU Images Predicts Poor Performance in Laparoscopic Surgery

There are large, and vitally important individual differences in aptitude for laparoscopic (‘keyhole’) surgery. Intuitively it seems likely that an important component is ability to recover the shape of 3-D structures (patients’ internal organs) from displays on a video monitor. The issue was studied empirically with PICSOR, a test based on research reported by Cowie and Byth (1995 Perception24 118 – 119). Subjects adjust a probe, which consists of a rotating arrowhead, until it appears perpendicular to a specified surface in a simple object (a sphere or a cube). Both probe and surface are depicted on a VDU screen. Measures of apparent slope are derived and related to the theoretical slope. Eight trainee surgeons were studied. They completed a battery of simulated laparoscopic tasks and the PICSOR tests. Two measures of performance on PICSOR were derived from simple regressions relating apparent and theoretical slope, R, and the slope of the fitted line. These were used in multiple regressions to predict performance in the simulated laparoscopic tasks. Performance on the PICSOR cubes task predicted performance in simulated surgery ( F2,7=29.5, p=0.0017). Both measures ( R and slope) contributed significantly. Relationships are probably not linear. One subject performed very badly on both PICSOR and simulated operations. If his data are excluded, both low R and high slope would appear to be related to poor laparoscopic performance. The nature of the area makes large-scale studies difficult, but the data suggest that they ought to be conducted.

The molecular basis of myelodysplastic syndromes

BACKGROUND AND OBJECTIVE

The myelodysplastic syndromes comprise a heterogeneous group of neoplastic disorders characterized by ineffective hematopoiesis with an increased tendency to evolve to acute leukemia. Clinically, the common manifestations include peripheral blood cytopenias of one or more lineages and a normal to hyperplastic marrow. MDS has been defined on the basis of morphological criteria, namely the percentage of blast cells in the bone marrow, by the French-American-British study group. Scoring systems have been developed to include such factors as hemoglobin, leukocyte count and age in the evaluation of MDS prognosis. Although useful in the prediction of clinical course and design of therapy regimens, our understanding of the basis of MDS has come from recent advances in molecular analysis of these disorders. This review describes some of the established and recent contributions to our understanding of the molecular basis of the myelodysplastic syndromes.

EVIDENCE AND INFORMATION SOURCES

The authors of the present review have been working in the field of myelodysplastic syndromes for several years and have contributed original papers on the molecular pathogenesis of these disorders. In addition, in the present review they have critically examined articles and abstracts published in journals covered by the Science Citation Index and Medline.

STATE OF ART AND PERSPECTIVES

Cytogenetic anomalies and proto-oncogene abnormalities point to new understanding of the pathogenesis of MDS as a sequence of DNA lesions leading to the evolution of the pre-malignant clone. The prognostic significance of these factors in predicting leukemic transformation and survival remains controversial. Characterization of MDS cells in vitro in response to combinations of exogenous growth factors have not only provided valuable information regarding ineffective hematopoiesis in MDS but have provided a new insight into treatment of MDS. One major development in our understanding of MDS is the possible explanation for the apparent paradox of a cellular marrow in combination with peripheral cytopenias. Extensive premature programmed cell death or apoptosis has been reported to be at least partly responsible. It will remain to be seen whether this fundamental characteristic of myelodysplastic hematopoiesis will play a central role in the drug or genetic based therapy in the myelodysplastic syndromes.

Bacterial glycoproteins: a link between glycosylation and proteolytic cleavage of a 19 kDa antigen from Mycobacterium tuberculosis

Protein glycosylation has an important influence on a broad range of molecular interactions in eukaryotes, but is comparatively rare in bacteria. Several antigens from Mycobacterium tuberculosis, the causative agent of human tuberculosis, have been identified as glycoproteins on the basis of lectin binding, or by detailed structural analysis. By production of a set of alkaline phosphatase (PhoA) hybrid proteins in a mycobacterial expression system, the peptide region required for glycosylation of the 19 kDa lipoprotein antigen from M.tuberculosis was defined. Mutagenesis of two threonine clusters within this region abolished lectin binding by PhoA hybrids and by the 19 kDa protein itself. Substitution of the threonine residues also resulted in generation of a series of smaller forms of the protein as a result of proteolysis. In a working model to account for these observations, we propose that the role of glycosylation is to regulate cleavage of a proteolytically sensitive linker region close to the acylated N-terminus of the protein.

Is developmental dyslexia a disconnection syndrome? Evidence from PET scanning

A rhyming and short-term memory task with visually presented letters were used to study brain activity in five compensated adult developmental dyslexics. Their only cognitive difficulty was in phonological processing, manifest in a wide range of tasks including spoonerisms, phonemic fluency and digit naming speed. PET scans showed that for the dyslexics, a subset only of the brain regions normally involved in phonological processing was activated: Broca's area during the rhyming task, temporo-parietal cortex during the short- term memory task. In contrast to normal controls these areas were not activated in concert. Furthermore the left insula was never activated. We propose that the defective phonological system of these dyslexics is due to weak connectivity between anterior and posterior language areas. This could be due to a dysfunctional left insula which may normally act as an anatomical bridge between Broca's area, superior temporal and inferior parietal cortex. The independent activation of the posterior and anterior speech areas in dyslexics supports the notion that representations of unsegmented and segmented phonology are functionally and anatomically separate.

Why are brain tumours still being missed?

The prediagnosis period of 74 children with primary brain tumours was assessed to examine their presentation and reasons for any delay in diagnosis. Medical case notes were reviewed and parents were interviewed and asked to complete psychological questionnaires. Mean (SD) duration of clinical history was 20.0 (29.1) weeks. Most common symptoms were vomiting (65%) and headache (64%). Only 34% of headaches were always associated with vomiting and only 28% occurred 'early morning'. Changes in the child's personality (47%) were also common. The average number of consultations before diagnosis was 4.6. Migraine was diagnosed in 24% of children and a psychological aetiology in 15%. One quarter of the children had altered levels of consciousness on arrival at the unit. Results indicate that delay in diagnosis still occurs, despite strong parental concern. The nonspecificity of symptoms and a high incidence of psychological symptoms may confound the clinical picture and are considered along with other possible contributory factors.

Aberrant expression of p21RAS but not p120GAP is a common feature of myelodysplasia

The RAS gene family encodes signal transducing proteins which are involved in the regulation of cell growth and differentiation. Constitutively 'activating' point mutations of RAS have been detected at high frequency in preleukaemia and acute leukaemia, however, the distribution of expression of p21RAS in normal or preleukaemic primary haematopoietic cells has not been studied. We have examined the expression of p21RAS and its negative regulator/downstream effector, p120GAP, in combination with lineage-specific cluster of differentiation markers in normal and preleukaemic myeloid bone marrow cells using flow cytometry. Normal bone marrow was characterized by low and uniform levels of p21RAS expression throughout all lineages analysed. In contrast, 28% (9/32) of patients with myelodysplastic syndrome (MDS) over-expressed p21RAS. In three of these patients a single over-expressing peak of p21RAS expression was observed, with no evidence of a population exhibiting expression within the normal range. In 6/32 MDS patients over-expression of p21RAS was observed only in a subpopulation of the myeloid cells. Follow-up samples were analysed in three of these six patients; over-expression was confirmed in each patient and in two patients a relative expansion of the over-expressing cell population was observed. Eight out of nine of the patients with aberrant p21RAS expression were diagnosed with low-risk MDS. From 21 MDS patients screened for p120GAP expression, no reduction or loss of expression was observed, however, one AML patient demonstrated a heterogeneous pattern of expression. p120GAP expression was lower (P < 0.05) in the AML group than in normals. The results of the study suggest that over-expression of the RAS gene product, p21RAS, may represent an alternative or additional mechanism of activation of the RAS signalling pathway and that this may play a role in leukaemogenesis, however, there is no evidence from this study that loss of p120GAP expression is a feature of myelodysplasia.

Expression of multiple DQB genes in Bos indicus cattle

Polymorphism of expressed bovine major histocompatibility complex (MHC) class II DQB genes was investigated in a group of nine MHC-homozygous Kenya Boran cattle (Bos indicus). DQB second exon fragments were amplified by reverse transcription-polymerase chain reaction of total mononuclear cell RNA, cloned and sequenced. While a single DQB sequence was obtained from some animals, two DQB exon 2 sequences were found in others, implying expression of duplicated DQB genes. Two pairs of duplicated DQB genes were found in this group of homozygotes, and sequence analysis showed that both pairs contained distinct DQB alleles. One DQB duplication was observed in two related animals with the same MHC haplotype (F100 and F188), while the second was detected in three animals (F187, G166 and G277) that expressed the same class II DRB3 and DQB alleles but had different class I (BoLA-A) types, suggesting that this DR/DQ haplotype may be widespread in Boran cattle.

Medical and nursing ethics: never the twain?

Since the publication of Carol Gilligan's In a different voice in 1982, there has been much discussion about masculine and feminine approaches to ethics. It has been suggested that an ethics of care, or a feminine ethics, is more appropriate for nursing practice, which contrasts with the 'traditional, masculine' ethics of medicine. It has been suggested that Nel Noddings' version of an 'ethics of care' (or feminine ethics) is an appropriate model for nursing ethics. The 'four principles' approach has become a popular model for medical or health care ethics. It will be suggested in this article that, whilst Noddings presents an interesting analysis of caring and the caring relationship, this has limitations. Rather than acting as an alternative to the 'four principles' approach, the latter is necessary to provide a framework to structure thinking and decision-making in health care. Further, it will be suggested that ethical separatism (that is, one ethics for nurses and one for doctors) in health care is not a progressive step for nurses or doctors. Three recommendations are made: that we promote a health care ethics that incorporates what is valuable in a 'traditional, masculine ethics', the why (four principles approach) and an 'ethics of care', the 'how' (aspects of Noddings' work and that of Urban Walker); that we encourage nurses and doctors to participate in the 'shared learning' and discussion of ethics; and that our ethical language and concerns are common to all, not split into unhelpful dichotomies.

A study of fluoxetine in obese elderly patients with type 2 diabetes

In order to establish the safety and efficacy of fluoxetine in subjects over 60 years of age with Type 2 diabetes, a randomized, double-blind, parallel study of 30 obese subjects was undertaken, comparing the use of fluoxetine 60 mg daily with placebo. Subjects were diet controlled with an HbA1 < 14% (reference range 6-9%) and BMI > 29 kg m2. Those taking fluoxetine had a median weight loss of 2.6 kg at 3 months (p < 0.001) and 3.9 kg at 6 months (p < 0.02), compared with weight loss in the placebo group of 0.1 kg and 0.0 kg at 3 and 6 months, respectively. Improved glycaemic control was also demonstrated in the fluoxetine group compared with placebo, initial HbA1 levels of 8.0% vs 8.7% (NS) falling at 4 months by 0.9% (p < 0.02) and at six months by 0.9% (p < 0.02). No sustained improvement in fasting blood glucose levels was demonstrated. Reporting of adverse events was similar in both groups. Fluoxetine in the short term aids weight loss and improves glycaemic control without a significant increase in adverse events in elderly Type 2 diabetic subjects.

Effect of administration and subsequent cessation of buserelin on cancellous bone of female rats

Although hormone replacement therapy is effective in preventing postmenopausal bone loss, it fails to cause a return of bone mass to normal in patients with established osteoporosis. Similarly, in the ovariectomized rat, estrogen administration protects the skeleton from bone loss but fails to reverse this once it has occurred. However, physiologically produced sex steroids may, in contrast to conventional methods of sex steroid administration, be capable of restoring bone mass in osteopenic states. To investigate this question, we analyzed the effect of treatment with the LHRH agonist buserelin for varying durations, and subsequent cessation thereof, on histomorphometric indices of rat cancellous bone. Female rats 13 weeks old were given daily SC injections of vehicle or buserelin as follows: vehicle days 1-90; vehicle days 1-150; vehicle days 1-60, buserelin days 61-90; vehicle days 1-60, buserelin days 61-90, vehicle days 91-150; vehicle days 1-30, buserelin days 31-90; vehicle days 1-30, buserelin days 31-90, vehicle days 91-150; buserelin days 1-90; buserelin days 1-90, vehicle days 91-150. At the end of the treatment period, animals were killed, tibiae removed, and histomorphometric indices assessed at the secondary spongiosa of the proximal metaphysis. Analysis of vaginal smears confirmed that buserelin rapidly suppressed ovulation, which quickly returned once treatment was stopped. We found that administration of buserelin for 30, 60, or 90 days reduced cancellous bone volume because of a reduction in both the number and thickness of trabeculae.(ABSTRACT TRUNCATED AT 250 WORDS)

5 alpha-Dihydrotestosterone partially restores cancellous bone volume in osteopenic ovariectomized rats

Although androgens are thought to be important for skeletal maintenance in females and males, little is known about the mechanisms involved. To investigate this question further, we examined the effects of administering 0.01, 0.1, or 1.0 mg/kg 5 alpha-dihydrotestosterone (DHT) for 60 days on the skeleton of ovariectomized rats. Treatment was delayed until 90 days after ovariectomy to enable bone loss to stabilize. We found that ovariectomy markedly reduced cancellous bone volume of the proximal tibial metaphysis due to a combination of loss and thinning of trabeculae. Cancellous bone volume was partially restored by all doses of DHT, with trabecular thickness, but not number, returning to that of sham-operated animals. DHT also stimulated longitudinal bone growth and endosteal and periosteal bone formation and suppressed histomorphometric indexes of cancellous bone resorption. This suggests that DHT influences skeletal metabolism in osteopenic ovariectomized rats both by stimulating bone formation and suppressing resorption, although it is unclear which, if any, of these actions predominate at cancellous sites.

The effects of ovarian transplantation on bone loss in ovariectomized rats

Although hormone replacement therapy can prevent postmenopausal bone loss, it does not restore bone mass to normal in patients with established osteoporosis. This might reflect a failure to reproduce certain aspects of gonadal function. One method of investigating this possibility would be to examine the effect of ovarian transplantation on the skeleton of osteopaenic ovariectomized rats. However, ovarian transplantation may not fully restore ovarian function to normal, and it is not known whether transplanted ovaries reproduce the action of native ovaries on the skeleton. Therefore, we investigated whether renal capsular or subcutaneous ovarian transplants prevent the effects of ovariectomy on histomorphometric indices of rat tibiae over 44 days. Daily vaginal smears showed that oestrous cycles returned in all but two of 25 animals receiving ovarian transplants. We found that ovarian transplantation prevented the reduction in cancellous bone volume following ovariectomy. While trabecular number was reduced in ovariectomized animals receiving renal capsular ovarian transplants compared to intact animals, trabecular thickness was increased in both transplant groups. Ovarian transplantation also prevented the increase in cancellous and cortical bone formation, cancellous bone resorption and longitudinal growth rate caused by ovariectomy. We conclude that restoration of ovarian function by ovarian transplantation largely prevents the effects of ovariectomy on histomorphometric indices of rat tibiae, suggesting that transplanted ovaries can substitute for the action of native ovaries on the skeleton.

Intermittent retinoic acid in combination with continuous oestradiol-17 beta increases cancellous bone volume in osteopaenic ovariectomized rats

Although short-term administration of oestradiol-17 beta (OE2) stimulates cancellous bone formation in the rat, this is replaced by a tendency to suppression after prolonged treatment. Hence, in rats rendered osteopaenic by ovariectomy, OE2 administration fails either to induce a sustained increase in bone formation or to restore bone volume. A possible explanation for this failure is that OE2 also inhibits bone resorption, secondarily suppressing bone formation through coupling mechanisms. We therefore investigated whether the effects of OE2 treatment might be modified by intermittently stimulating bone resorption with retinoic acid (120mg/kg daily) for 4 out of every 20 days. We found, in a preliminary experiment using intact animals, that intermittent retinoic acid reduced cancellous bone volume, consistent with previously documented stimulation of bone resorption by retinoic acid. Rats were then rendered osteopaenic by ovariectomy, and given vehicle, retinoic acid and/or OE2. We found that animals treated with intermittent retinoic acid and OE2 showed a substantial increase in cancellous bone volume compared with ovariectomized animals treated with vehicle, retinoic acid alone or OE2 alone. Therefore, intermittent retinoic acid appears to cause a net increase in bone formation over resorption when given to ovariectomized animals in conjunction with OE2. We conclude that the effects of OE2 on cancellous bone are modified by intermittent treatment with retinoic acid, resulting in a substantial increase in bone volume.

Response of insulin-like growth factor (IGF)-binding protein-1 (IGFBP-1) and IGFBP-3 to IGF-I treatment in severe insulin resistance

It has been suggested that recombinant human IGF-I (rhIGF-I) is a potential therapeutic agent in diabetes mellitus. It is known to have glucose-lowering effects in normal individuals, in patients with non-insulin-dependent diabetes (NIDDM) and in extreme insulin-resistant states. IGF-binding proteins (IGFBPs) have the potential to affect the biological activity of rhIGF-I. We have studied the effect of infused rhIGF-I on IGFBP-1 and IGFBP-3 in a patient with Mendenhall's syndrome, a rare insulin-resistant state. During an infusion of 20 mg rhIGF-I, glucose concentrations fell from 44.1 +/- 7.2 to 31.5 +/- 7.2 (S.E.M.) mmol/l (P = 0.001), and insulin and C-peptide levels fell from 920 +/- 62 to 542 +/- 45 mU/l (P = 0.008) and 5466 +/- 633 to 3071 +/- 297 pmol/l (P = 0.02) respectively. Significant lowering of phosphate, magnesium and alkaline phosphatase concentrations was also noted. IGF-I levels rose from 48 +/- 10.2 to 410 +/- 50.1 micrograms/l (P = 0.001), and those of IGF-II fell from 279.8 +/- 8.3 to 104.3 +/- 7.9 micrograms/l (P = 0.001). IGFBP-1 concentrations did not significantly change during the infusion but those of IGFBP-3 increased from 1655 +/- 127 to 2197 +/- 334 micrograms/l (P = 0.002), despite a significant fall in GH concentrations from 10.7 +/- 2.6 to 4.1 +/- 1.1 mU/l (P = 0.007), suggesting that IGFBP-3 regulation is also IGF-I-dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

The estrogen antagonist ICI 182,780 reduces cancellous bone volume in female rats

Although estrogen is thought to protect the skeleton by inhibiting bone resorption, we have also found that in the rat, estrogen stimulates cancellous bone formation. However, the extent to which the various skeletal actions of estrogen are mediated by classical estrogen receptors remains unclear. Although estrogen receptor antagonists such as tamoxifen have been used to study this question, interpretation of the results is complicated by the fact that this agent also acts as a partial estrogen agonist. However, the recent development of estrogen antagonists devoid of agonist activity provides an opportunity to explore this question further. We, therefore, investigated the effect of administration of the pure estrogen antagonist ICI 182,780 on the skeleton of adult female rats. We found that ICI 182,780 reduced bone volume at the proximal tibial metaphysis by approximately 30%, associated with an increase in osteoclast surface. We then investigated the effect of ICI 182,780 on the anabolic action of estrogen. We used ovariectomized rats treated with 3-amino-1-hydroxypropylidene-1-bisphosphonate to inhibit bone resorption, thereby preventing any increase in bone formation as a result of the stimulation of bone resorption due to estrogen deficiency. 17 beta-Estradiol (1 micrograms/kg) stimulated cancellous bone formation in such animals by approximately 8-fold; this increase was abolished when ICI 182,780 was also given. In contrast, ICI 182,780 affected neither longitudinal nor periosteal tibial growth in either intact animals or ovariectomized rats given estradiol or vehicle. We conclude that ICI 182,780 reduces cancellous bone volume in the rat by antagonizing estrogen's actions on bone formation and resorption, suggesting that these processes are both mediated by classical estrogen receptors.