Effects of maternal vitamin B12 supplementation on early infant neurocognitive outcomes: a randomized controlled clinical trial

Maternal nutritional status during pregnancy impacts fetal brain development. Vitamin B12 plays a vital role in neuronal development. However, findings from studies on the association between maternal B12 status and child cognitive functions have been inconsistent. We performed a randomized, placebo‐controlled clinical trial of oral B12 supplementation (50 µg) beginning at <14 weeks of gestation through a 6‐week post‐partum. In the present study, we report the effects of maternal B12 supplementation on cognitive development in infants at 9 months of age on Bayley Scales of Infant Development‐III (BSID‐III). One hundred eighty‐three pregnant women received vitamin B12, and 183 received placebo. Nine‐month BSID‐III development score was available in 178 infants. There were no significant differences in maternal sociodemographic characteristics and baseline biochemical measures between infants who underwent BSID‐III evaluation and infants who were not evaluated. There were no significant differences in any of the subscales of BSID‐III between infants born to mothers who received B12 supplementation (n = 78) vs. placebo (n = 100). On multiple regression analysis, elevated maternal total homocysteine (tHcy) levels adjusted for treatment group, birthweight, parity, income and home environment at second trimester of pregnancy were significantly negatively associated with expressive language (β = 3.13 points, P < 0.001), and in third trimester of pregnancy with expressive language (β = ?2.29 points, P < 0.001) and fine motor (β = ?1.41 points, P = 0.005) domains of BSID‐III. While no significant effects of maternal B12 supplementation were seen on cognitive development in infants at 9 months of age, elevated maternal tHcy levels were associated with poorer cognitive performance in some of the subdomains of BSID‐III. In pregnant women with elevated tHcy levels and or B12 deficiencies, it may be worthwhile to study the impact of longer term maternal supplementation on infant cognitive outcomes.     

Genetic epidemiology of muscular dystrophies resulting from sarcoglycan gene mutations.

BACKGROUND: The autosomal recessive limb-girdle muscular dystrophies (LGMDs) are a group of genetically heterogeneous muscle diseases characterised by progressive proximal limb muscle weakness. Six different loci have been mapped and pathogenetic mutations in the genes encoding the sarcoglycan complex components (alpha-, beta-, gamma-, and delta-sarcoglycan) have been documented. LGMD patients affected with primary "sarcoglycanopathies" are classified as LGMD2D, 2E, 2C, and 2F, respectively. METHODS: A geographical area in north east Italy (2,319,147 inhabitants) was selected for a genetic epidemiological study on primary sarcoglycanopathies. Within the period 1982 to 1996, all patients living in this region and diagnosed with muscular dystrophy were seen at our centre. Immunohistochemical and immunoblot screening for alpha-sarcoglycan protein deficiency was performed on all muscle biopsies from patients with a progressive muscular dystrophy of unknown aetiology and normal dystrophin. Sarcoglycan mutation analyses were conducted on all patient muscle biopsies shown to have complete or partial absence of alpha-sarcoglycan immunostaining or a decreased quantity of alpha-sarcoglycan protein on immunoblotting. RESULTS: Two hundred and four patient muscle biopsies were screened for alpha-sarcoglycan protein deficiency and 18 biopsies showed a deficiency. Pathogenetic mutations involving one gene for sarcoglycan complex components were identified in 13 patients: alpha-sarcoglycan in seven, beta-sarcoglycan in two, gamma-sarcoglycan in four, and none in the delta-sarcoglycan gene. The overall prevalence of primary sarcoglycanopathies, as of 31 December 1996, was estimated to be 5.6 x 10(-6) inhabitants. CONCLUSION: The prevalence rate estimated in this study is the first to be obtained after biochemical and molecular genetic screening for sarcoglycan defects.     

Evidence for selection of a population of multi-reactive B cells into the splenic marginal zone

Antibody reactivity to self-antigens is a normal component of the immune system. To study the mechanism by which self-reactive B cells are generated and maintained, we analyzed B cell development in transgenic mice that express a rearranged VH81X heavy chain from the pre-immune repertoire. In these mice, > 95% of B cells express the transgene in association with a variety of kappa light chains but V kappa 1 C being the dominant light chain. These transgenic B cells with identical V kappa 1C-J kappa 5 joins do not normally secrete IgM in vivo, but antibodies derived from these B cells, through LPS activation in vitro or after hybridoma immortalization, are self-reactive and recognize an ubiquitous epitope(s) on intracytoplasmic proteins from different tissues. They have the phenotype and localization pattern of long-lived marginal zone B cells and their development in vivo is blocked by injection of soluble VH81X-V kappa 1CJ kappa 5 IgM antibody. The observations in this transgenic mouse provide evidence for positive selection of a population of self-reactive B cells. These B cells enter the peripheral pool of B cells where they localize in the marginal zone of the spleen and, in contrast to other transgene-expressing B cells, do not secrete IgM antibody.      

Immunophenotyping of non-Hodgkin's lymphomas in paraffin-embedded tissue sections. A comparison with genotypic analysis.

Several monoclonal antibodies (MoAbs) are now available for immunophenotyping non-Hodgkin's lymphomas (NHLs) in paraffin-embedded tissue sections. To determine the reliability of these reagents in predicting the genotype, 44 cases of NHL were studied with the alkaline phosphatase-anti-alkaline phosphatase technique with the use of the following MoAbs: leukocyte common antigen (CD45), Mac 387, L26, 4KB5, MB1, MB2, LN2, UCHL1, MT1, and MT2. The lineage of the neoplastic cells was determined in all cases by gene rearrangement studies for immunoglobulin heavy chain and for the T-cell receptor beta-chain. Genotypic results showed B-cell lineage in 33 cases (75%), T-cell lineage in 6 cases (14%), and mixed or undetermined lineage in 5 cases (11%). A concordance of lineage assignment by paraffin section immunophenotyping with gene rearrangement studies was observed in 37 of 39 (95%) lymphomas with an unequivocally defined genotype. MoAb L26 was the most sensitive in detecting B-cell genotype; MoAbs MT1 and UCHL1 were the most sensitive and specific, respectively, in detecting T-cell genotype. The authors conclude that lineage assignment of NHLs in paraffin sections is reflective of the corresponding genotype when an appropriate panel of MoAbs is used.     

Gene-expression profiles in hereditary breast cancer

BACKGROUND: Many cases of hereditary breast cancer are due to mutations in either the BRCA1 or the BRCA2 gene. The histopathological changes in these cancers are often characteristic of the mutant gene. We hypothesized that the genes expressed by these two types of tumors are also distinctive, perhaps allowing us to identify cases of hereditary breast cancer on the basis of gene-expression profiles. METHODS: RNA from samples of primary tumor from seven carriers of the BRCA1 mutation, seven carriers of the BRCA2 mutation, and seven patients with sporadic cases of breast cancer was compared with a microarray of 6512 complementary DNA clones of 5361 genes. Statistical analyses were used to identify a set of genes that could distinguish the BRCA1 genotype from the BRCA2 genotype. RESULTS: Permutation analysis of multivariate classification functions established that the gene-expression profiles of tumors with BRCA1 mutations, tumors with BRCA2 mutations, and sporadic tumors differed significantly from each other. An analysis of variance between the levels of gene expression and the genotype of the samples identified 176 genes that were differentially expressed in tumors with BRCA1 mutations and tumors with BRCA2 mutations. Given the known properties of some of the genes in this panel, our findings indicate that there are functional differences between breast tumors with BRCA1 mutations and those with BRCA2 mutations. CONCLUSIONS: Significantly different groups of genes are expressed by breast cancers with BRCA1 mutations and breast cancers with BRCA2 mutations. Our results suggest that a heritable mutation influences the gene-expression profile of the cancer.     

Increased responsiveness of rat dorsal horn neurons in vivo following prolonged intrathecal exposure to interferon-gamma

Prolonged increases in the level of the pro-inflammatory cytokine interferon-gamma occur in the CNS during some disease states associated with persistent pain. Administration of interferon-gamma to both humans and rodents has produced pain or pain-related behavior but the underlying mechanisms are unknown. The present study examined the effects of repeated intrathecal administration of interferon-gamma on dorsal horn neuronal responses under in vivo conditions. In addition, behavioral effects of interferon-gamma treatment were studied. Intrathecal cannulae were implanted into anesthetized rats. Animals then received either 1000 U of recombinant rat interferon-gamma in 10 microl buffer intrathecally, repeated four times over 8 days, or similarly administered buffer (controls). Interferon-gamma-treated animals showed a significant reduction in paw withdrawal threshold to mechanical stimulation of the hind paw. Electrophysiological experiments were performed under halothane anesthesia. Extracellular recordings of spontaneous and evoked responses were obtained from dorsal horn neurons (n=64) in the lumbar spinal cord. There was a significantly higher proportion of spontaneously active neurons in the interferon-gamma-treated animals (50%) when compared with controls (19%). A significantly increased proportion of neurons from interferon-gamma-treated animals displayed afterdischarges following both innocuous and noxious mechanical stimulation of the receptive field (brush: 21% in interferon-gamma-treated, 3% in controls; pinch: 97% in interferon-gamma-treated, 50% in controls). Neurons from interferon-gamma-treated animals also showed significantly increased wind-up of action potentials in response to repeated electrical stimulation of the sciatic nerve at C-fiber strength at both 0.5 and 1 Hz. Paired-pulse inhibition, evoked through electrical stimulation of the cutaneous receptive field, was significantly decreased in neurons from interferon-gamma-treated animals at 50 and 100 ms inter-stimulus intervals. We propose that this demonstrated reduction in inhibition may underlie the enhanced excitatory responses. Such interferon-gamma-induced changes in evoked responses may contribute to persistent pain following damage or disease states in the nervous system.     

Does recurrent depression lead to a change in neuroticism?

The hypothesis that recurrent or chronic depressive illness produces a long-term change in neuroticism was examined in a sample (N = 34) from a consecutive series of 89 depressed patients admitted to the Maudsley Hospital in 1965/6. The Eysenck Personality Inventory (EPI) was administered at the time of the index illness both when the patients were depressed and on recovery, and then again at follow-up 18 years later. The change in the neuroticism (N) score over the 18-year-period was compared in good and poor outcome groups defined variously by a global rating of outcome, frequency of episodes, extent of subsequent hospitalization and the presence or absence of subsequent chronicity. The mean N score for the sample as a whole did not change significantly over the 18 years, and no differential change in the N score was observed between any of the good and poor outcome groups. Thus, the hypothesis was not supported.     

Thalamic neuronal activity in rats with mechanical allodynia following contusive spinal cord injury

Pain and allodynia following spinal cord injury are poorly understood and difficult to treat. Since there is evidence that supraspinal mechanisms are important in such pain, we have studied the role of the thalamus in an experimental model of spinal injury. Extracellular recordings were obtained from neurones of the thalamic nucleus ventralis postero-lateralis (VPL) in normal rats and those which had sustained a contusive spinal cord injury to the thoraco-lumbar junction 7 days previously. Behavioural testing with von Frey hairs established that 11 spinally injured rats showed exaggerated vocal responses to normally innocuous mechanical stimulation (allodynia) whereas eight were non-allodynic. Thalamic VPL neurones in spinally injured rats (both allodynic and non-allodynic) exhibited a dysrhythmia in that a significantly higher proportion fired spontaneously in an oscillatory mode when compared with neurones in uninjured rats. Thus this dysrhythmia was linked to spinal injury, not to allodynia. The evoked responses of VPL thalamic neurones to brushing the skin, however, were significantly elevated in allodynic rats when compared with those in uninjured rats and neuronal afterdischarges to these stimuli (which were absent in uninjured rats) were more common in allodynic than in non-allodynic rats. We have previously reported that a proportion of spinal neurones in allodynic spinally injured rats show increased evoked responses and afterdischarges following brushing the skin and hence the enhanced thalamic responses may reflect a greater spinal input. In view of the increasing evidence that thalamo-cortical rhythmical firing is linked to sensorimotor and cognitive brain functions, we propose that pain following brushing the skin results from an exaggerated spinal input being processed by a dysrhythmic thalamus. Thus both spinal and thalamic mechanisms may be important in the genesis of pain and allodynia following spinal cord injury.     

Persistence of immunoreactive neurokinins in the dorsal horn of barbiturate anaesthetized and spinal cats, following release by tibial nerve stimulation

Antibody-coated microprobes were used to study the time course of release and disappearance of immunoreactive neurokinins in the dorsal spinal cord, in response to electrical stimulation of unmyelinated fibres of the tibial nerve of the cat. Noxious cutaneous stimuli were not used thereby avoiding potentially uncontrolled tissue damage and inflammation. Microprobes, inserted into the spinal cords of barbiturated anaesthetized spinal cats prior to nerve stimulation, detected a basal level of immunoreactive neurokinins. During nerve stimulation immunoreactive neurokinins were released significantly in the upper dorsal horn and dorsal columns and required at least 1 h to return to prestimulus levels. The persistence of immunoreactive neurokinins in the dorsal horn may underlie the prolonged hyperexcitability of some spinal neurons following brief noxious stimuli.