Potent inhibition by ropivacaine of metastatic colon cancer SW620 cell invasion and NaV1.5 channel function.

BACKGROUND: Metastatic breast and colon cancer cells express neonatal and adult splice variants of NaV1.5 voltage-activated Na(+) channels (VASCs). Block of VASCs inhibits cell invasion. Local anaesthetics used during surgical tumour excision inhibit VASC activity on nociceptive neurones providing regional anaesthesia. Inhibition of VASCs on circulating metastatic cancer cells may also be beneficial during the perioperative period. However, ropivacaine, frequently used to provide analgesia during tumour resection, has not been tested on colon cancer cell VASC function or invasion. METHODS: We used reverse transcription-polymerase chain reaction and sequencing to identify NaV1.5 variants in the SW620 metastatic colon cancer cell line. Recombinant adult and neonatal NaV1.5 variants were expressed in human embryonic kidney cells. Voltage-clamp recordings and invasion assays were used to examine the effects of ropivacaine on recombinant NaV1.5 channels and the metastatic potential of SW620 cells, respectively. RESULTS: SW620 cells expressed adult and neonatal NaV1.5 variants, which had similar steady-state inactivation profiles, but distinctive activation curves with the neonatal variant having a V1/2 of activation 7.8 mV more depolarized than the adult variant. Ropivacaine caused a concentration-dependent block of both NaV1.5 variants, with IC50 values of 2.5 and 3.9 µM, respectively. However, the reduction in available steady-state current was selective for neonatal NaV1.5 channels. Ropivacaine inhibited SW620 invasion, with a potency similar to that of inhibition of NaV1.5 channels (3.8 µM). CONCLUSIONS: Ropivacaine is a potent inhibitor of both NaV1.5 channel activity and metastatic colon cancer cell invasion, which may be beneficial during surgical colon cancer excision.

Oral zinc augmentation with vitamins A and D increases plasma zinc concentration: implications for burden of disease.

A study evaluating zinc supplementation in patients with Alzheimer's disease yielded variable zinc plasma levels in spite of positive cognitive and physiological results. In an attempt to raise and sustain plasma zinc levels, a single patient was given 15 mg zinc/day with various combinations of vitamins. A sustained raise in plasma zinc concentration (and therefore its potential bioavailability) was obtained only when the zinc was augmented with both vitamins A and D (in RDA concentrations). In order to verify these results, a follow-up study was conducted in 70 volunteers. Seven groups of 10 healthy subjects received various combinations of zinc and the two vitamins A and D, namely: zinc, vitamin A, vitamin D, zinc plus vitamin A, zinc plus vitamin D, vitamins A and D, and zinc plus vitamins A and D. Plasma zinc levels were determined at baseline, 3 weeks and 6 weeks. Plasma zinc levels increased significantly (p < 0.02) from 11.82 (+/-2.60) to 13.32 (+/-3.04) mum/L only in the group receiving the combination of zinc and vitamins A and D. This novel method of increasing plasma zinc levels by the augmentation of vitamins A and D may have implications for the reduction of burden of disease.

The effect of stress on the antioxidative potential of serum: implications for Alzheimer's disease.

There is growing consensus in the literature that oxidation status is increased in Alzheimer's disease (AD), and that antioxidant supplementation as prevention or treatment strategy should be investigated further. In the present study the total antioxidant status (TAS) was found to be highly significantly lower in 22 AD patients (p < 0.0001) than in 22 age- and gender matched non-demented controls. The TAS was also lower than controls in 22 patients with vascular dementia, but not significantly. The increased oxidation status in AD was verified using the benzoate hydroxylation method. The origin of the enhanced oxidation status in AD has not been elucidated. To determine whether a causal effect between stress and oxidative status of serum can be demonstrated, a rat model was used with two different kinds of stressors, swim stress (exercise) and restraint stress (non-exercise stress). Following swim stress the maximum oxidative effect was observed at one hour post stress (p < 0.001). At 24 h the oxidative status had recovered significantly to below control values. Restraint stress, however, showed progressively increased oxidation which attained significance after 24 h (p < 0.005). It is postulated that stress may contribute to the higher oxidation status in AD patients.

Iron and the folate-vitamin B12-methylation pathway in multiple sclerosis.

UNLABELLED: Some subjects with multiple sclerosis (MS) present with low blood iron parameters. Anecdotal reports and a single patient study suggest that iron supplementation may be beneficial in these subjects. Myelin is regenerated continually, but prerequisites for this process are iron and a functional folate-vitamin B12-methylation pathway. The aim of this study was to determine iron status, folate and homocysteine in MS subjects, and to evaluate the effect on MS symptoms if deficiencies were addressed. RESULTS: In relapsing-remitting MS subjects, serum iron concentration correlated significantly with age at diagnosis (r=0.49; p=0.008). In Caucasian female MS subjects, serum iron and ferritin concentrations were significantly lower than in matched controls. In a 6-month pilot study, 12 subjects taking a regimen of nutritional supplements designed to promote myelin regeneration, improved significantly neurologically as measured by the Kurzke EDSS (Total Score means 3.50 to 2.45, 29.9%; p=0.021). These were significantly improved (p=0.002) compared to 6 control group patients taking multivitamins (Kurzke Score increased by 13.9% from 4.83 to 5.50). Both groups had significantly reduced homocysteine concentrations at 6 months, suggesting that methylation is necessary but not sufficient for myelin regeneration.

Mycobacterial growth in human macrophages: variation according to donor, inoculum and bacterial strain.

The microbicidal capacity of the macrophage is frequently evaded by mycobacteria, leading to tuberculosis (TB). We investigated a number of parameters affecting the rate of growth of mycobacteria in human monocyte-derived macrophages (MDM). The results show a great deal of variation in the growth of both Mycobacterium bovis BCG and M. tuberculosis H37Rv, using a large number of human macrophage donors, (132 and 40, respectively), but no correlation was seen with the TB status of the MDM donor. Clumping of the mycobacteria resulted in more vigorous growth in MDM, suggesting that inoculum size could affect disease progression. The growth rates of 17 clinical isolates of M. tuberculosis were measured in macrophages derived from three donors and no consistent or marked differences between isolates were observed over the 5-day period of growth measurement. However, all 17 clinical strains grew consistently faster than H37Rv in the same experiments.

Mannose-binding protein B allele confers protection against tuberculous meningitis.

Inhalation is the principal mode of entry for Mycobacterium tuberculosis in humans. Primary infection is usually restricted to the lungs and contiguous lymph nodes. In a subset of infected individuals, predominantly children, the infection is spread hematogenously to the meninges. The host factors that influence the development of tuberculous meningitis have not been well elucidated. The mannose-binding protein (MBP), a serum protein, is considered as an "ante-antibody." MBP has been shown to bind mycobacteria and acts as an opsonin in vitro. Although MBP plays a role in first-line host defense, it may under certain circumstances be deleterious to the host. In tuberculosis (TB), MBP may assist the spread of this intracellular pathogen. Therefore, we hypothesized that MBP genotypes that result in a phenotype of low MBP levels might be protective. We studied a well-defined South African population in which TB has reached epidemic levels. We found that the MBP B allele (G54D), which disrupts the collagen region of the protein and results in low MBP levels, was found in 22 of 79 (28%) of the TB-negative controls from the same community, compared with 12 of 91 (13%) of the patients with pulmonary TB (p < 0.017), and 5 of 64 (8%) of patients with tuberculous meningitis (p < 0.002). In addition, we found significantly lower serum MBP concentrations in TB-negative controls compared with postacute phase, fully recovered TB patients (p < 0.004). These findings suggest that the MBP B allele affords protection against tuberculous meningitis.

Potentiation of isoniazid activity against Mycobacterium tuberculosis by melatonin.

The limited number of effective antituberculosis drugs available necessitates optimizing current treatments. We show that melatonin, which is synthesized in the pineal gland, can cause at least a threefold increase in the efficacy of isoniazid. This suggests that tuberculosis chemotherapy can be improved by innate molecules such as melatonin.

Crack-induced enteric ischemia.

Rare instances of intestinal ischemia subsequent to cocaine use have been reported. Crack abuse, linked to gastroduodenal ulcer perforation, has not been associated with mesenteric infarction until this case report.