Hyperhomocysteinemia in type 2 diabetes mellitus: cardiovascular risk factors and effect of treatment with folic acid and pyridoxine

OBJECTIVE

To determine whether hyperhomocysteinemia (HH) exacerbates other cardiovascular risk factors and markers of coagulation and hemostasis in patients with type 2 diabetes mellitus (DM) and whether treatment of HH with vitamins will alter these risk factors.

METHODS

We measured several cardiovascular risk factors and markers of coagulation and hemostasis in patients with type 2 DM with and without HH. We also treated patients with type 2 DM and coexistent HH with high doses of folic acid and pyridoxine to determine whether this treatment would lower plasma total homocysteine concentrations as well as correct other associated cardiovascular risk factors in this population.

RESULTS

Plasma levels of plasminogen activator inhibitor type 1 and fibrinogen were significantly higher in all patients with DM in comparison with control subjects (P<0.01), whether they had HH or not. No significant difference was noted between the two groups of patients with DM. The presence of hypertension and microalbuminuria did not lead to a higher plasma total homocysteine. After treatment with folic acid, 15 mg daily, and pyridoxine, 600 mg daily, fasting (basal) plasma total homocysteine declined significantly in patients with DM from 12.3 +/- 2.9 micromol/L to 9.1 +/- 1.1 micromol/L (P<0.01). The peak post-methionine load plasma total homocysteine in the patients with DM decreased from 39.9 +/- 11.4 micromol/L to 30.4 +/- 6.5 micromol/L (P<0.05). Neither fasting nor peak plasma total homocysteine changed in normal subjects. None of the cardiovascular risk factors measured changed significantly with the vitamin treatment.

CONCLUSION

The coexistence of type 2 DM and HH does not lead to an exacerbation of abnormalities in the measured variables of coagulation and hemostasis. Treatment with high doses of folic acid and pyridoxine lowers the plasma total homocysteine significantly but does not improve any of the associated cardiovascular risk factors that we measured. Long-term clinical trials should be conducted to determine whether high-dose vitamin treatment will diminish the increased morbidity and mortality associated with cardiovascular disease in patients with type 2 DM.

Endocytosis and nuclear trafficking of adeno-associated virus type 2 are controlled by rac1 and phosphatidylinositol-3 kinase activation

Adeno-associated virus (AAV) is a single-stranded DNA parvovirus that causes no currently known pathology in humans. Despite the fact that this virus is of increasing interest to molecular medicine as a vector for gene delivery, relatively little is known about the cellular mechanisms controlling infection. In this study, we have examined endocytic and intracellular trafficking of AAV-2 using fluorescent (Cy3)-conjugated viral particles and molecular techniques. Our results demonstrate that internalization of heparan sulfate proteoglycan-bound AAV-2 requires alphaVbeta5 integrin and activation of the small GTP-binding protein Rac1. Following endocytosis, activation of a phosphatidylinositol-3 (PI3) kinase pathway was necessary to initiate intracellular movement of AAV-2 to the nucleus via both microfilaments and microtubules. Inhibition of Rac1 using a dominant N17Rac1 mutant led to a decrease in AAV-2-mediated PI3 kinase activation, indicating that Rac1 may act proximal to PI3 kinase during AAV-2 infection. In summary, our results indicate that alphaVbeta5 integrin-mediated endocytosis of AAV-2 occurs through a Rac1 and PI3 kinase activation cascade, which directs viral movement along the cytoskeletal network to the nucleus.

An evaluation of the synapse specificity of long-term depression induced in rat cerebellar slices

Whole-cell excitatory postsynaptic currents (EPSCs) were recorded from single Purkinje cells (PCs) in rat cerebellar slices in response to alternate activation of two separate sets of parallel fibres (PF1 and PF2). Pairing the stimulation of one input (PF1) with PC depolarisation at 1 Hz for 5 min produced varied effects, including a long-term depression (LTD) of subsequent responses, a medium-term potentiation, or no change relative to baseline levels (n = 14). In all but two cases PF2 responses mirrored those in PF1, in both direction and magnitude even though this second pathway was not specifically activated during pairing. Increasing the stimulus strength to evoke larger amplitude EPSCs (> 1000 pA) dramatically increased the proportion of cells that underwent LTD in both PF1 and PF2. LTD in both pathways was postsynaptic calcium dependent. PC depolarisation alone (n = 7) or PF1 stimulation paired with PC hyperpolarisation (n = 6) failed to induce LTD at either site. Pairing PF1 stimulation with climbing fibre (CF) activation at 1 Hz for 5 min produced LTD in the majority of cells regardless of the strength of PF stimulation. LTD under these conditions was not, however, input specific, even at the lowest stimulus strengths. With EPSCs greater than 1000 pA in amplitude, depression was apparent in both pathways even when the duration of PF1 pairing with depolarisation was limited to 1 min. Full expression of LTD in PF2 required stimulation of this pathway to be resumed within a distinct temporal window of conjunctive pairing with PF1. Introducing a delay of 20 min before resumption of PF2 activation preserved the input specificity of synaptic depression. We conclude that pairing either PC depolarisation or CF activation with stimulation of a discrete set of PFs produces LTD that spreads to adjacent synapses on the same PC.

An investigation into the use of serum albumin in pressure sore prediction

OBJECTIVES

To ascertain the relevance of serum albumin and serum sodium as predictors of pressure sores in addition to the Waterlow score.

DESIGN

Observational study of patients at risk of developing decubitus ulcers.

SETTING

Staffordshire, in the midlands of the United Kingdom.

PARTICIPANTS

773 elderly hospital in-patients of a district general hospital.

MEASUREMENTS

Waterlow scores and serum albumin and sodium. Development of a pressure sore.

RESULTS

Logistic regression analysis of serum albumin, serum sodium and the Waterlow score showed the Waterlow score and serum albumin were significant predictors of pressure sores.

CONCLUSIONS

Serum albumin may, in this patient group (in-patients over 64 years of age), be a useful predictor of pressure sore occurrence, though further work is needed to establish whether this is the case. Risk assessment of pressure sores can possibly be improved by adding serum albumin to one of the pre-existing tools such as the Waterlow score.

Double mutation (A171T and D444H) is a common cause of profound biotinidase deficiency in children ascertained by newborn screening the the United States. Mutations in brief no. 128. Online

Biotinidase deficiency is inherited as an antosomal recessive trait that, unless treated with pharmacologic doses of biotin, can result in neurologic and cutaneous symptoms. We have identified two new mutations in exon D of the biotinidase gene of children with profound biotinidase deficiency ascertained by newborn screening. Transition 511G->A near the 5' end of exon D results in a substitution of threonine for alanine 171 (A171T) and transversion 1330G->C occurs close to the 3' end of exon D causing a substitution of histidine for aspartic acid 444 (D444H). The D444H mutation was detected in four individuals from our normal population whose mean serum biotinidase activity is 5.25 nmol/min/ml, which is significantly lower than the mean normal activity (7.1 nmol/min/ml). We calculated that this mutation causes a 52% loss of activity in the aberrant enzyme. Twenty-three individuals with the D444H mutation were found by allele specific oligonucleotide analysis of DNA from 296 randomly-selected, anonymous dried-blood spots. We estimate the frequency of this allele in the general population to be 0.039. In contrast, no individuals in 376 have the A171T mutation. Fourteen children (eleven probands and three siblings) out of the 31 enzyme-deficient children have both the A171T and D444H mutations. Both mutations are inherited from a single parent as a double mutation allele. The nine families in which this allele was identified are of mostly European ancestry, although the mutation cannot be attributed to a specific nationality or ethnic group. The serum of a child who is homozygous for the double mutation allele has very little CRM and the aberrant enzyme has very low biotinylhydrolase activity and no botinyl-transferase activity. This double mutation allele (A171T and D444H) is a common cause of profound biotinidase deficience in children ascertained by newborn screening in the United States.

Camberwell Assessment of Need for the Elderly (CANE). Development, validity and reliability

BACKGROUND

There exists no instrument specifically designed to measure comprehensively the needs of older people with mental disorders.

AIM

To develop such an instrument which would take account of patients', staff and careers' views on needs.

METHOD

Following an extensive development process, the assessment instrument was subjected to a test-retest and interrater reliability study, while aspects of validity were addressed both during development and with data provided by sites in the UK, Sweden and the USA.

RESULTS

The Camberwell Assessment of Need for the Elderly (CANE) comprises 24 items (plus two items for career needs), and records staff, career and patient views. It has good content, construct and consensual validity. It also demonstrates appropriate criterion validity. Reliability is generally very high: kappa > 0.85 for all staff ratings of interrater reliability. Correlations of interrater and test-retest reliability of total numbers of needs identified by staff were 0.99 and 0.93, respectively.

CONCLUSIONS

The psychometric properties of the CANE seem to be highly acceptable. It was easily used by a wide range of professionals without formal training.

Aloe vera leaf gel: a review update

Research since the 1986 review has largely upheld the therapeutic claims made in the earlier papers and indeed extended them into other areas. Treatment of inflammation is still the key effect for most types of healing but it is now realized that this is a complex process and that many of its constituent processes may be addressed in different ways by different gel components. A common theme running though much recent research is the immunomodulatory properties of the gel polysaccharides, especially the acetylated mannans from Aloe vera, which are now a proprietary substance covered by many patents. There have also been, however, persistent reports of active glycoprotein fractions from both Aloe vera and Aloe arborescens. There are also cautionary investigations warning of possible allergic effects on some patients. Reports also describe antidiabetic, anticancer and antibiotic activities, so we may expect to see a widening use of aloe gel. Several reputable suppliers produce a stabilized aloe gel for use as itself or in formulations and there may be moves towards isolating and eventually providing verified active ingredients in dosable quantities