Assessment of the effects of cinnamon leaf oil on rumen microbial fermentation using two continuous culture systems.

Two continuous culture (CC) systems, the rumen simulation technique (Rusitec) and a dual-flow (DF) fermenter, were used to evaluate effects of the essential oil from cinnamon leaf (CIN) on rumen microbial fermentation. Incubations (d 1 through 8 for adaptation and d 9 through 16 for sampling) were conducted concurrently in the 2 systems, with CIN added at 0 (control) and 500 mg/L of rumen fluid culture. Eight Rusitec (920 mL; dilution rate = 2.9%/h) and 6 DF (1,300 mL; dilution rate = 6.3%/h) fermenters were randomly assigned to treatment. Inoculum was prepared from 4 ruminally cannulated lactating Holstein cows fed a total mixed ration consisting of 51% forage and 49% concentrate (dry matter basis). Ruminal pH, total volatile fatty acid (VFA) concentration, and diet digestibility were reduced by CIN addition in the Rusitec but were not affected by CIN administration in the DF. The addition of CIN in the Rusitec decreased apparent N disappearance, NH3-N concentration, and molar proportions of branched-chain VFA. In contrast, in the DF no effect of CIN was observed on apparent N degradation, NH3-N concentration, and molar proportion of branched-chain VFA. In the Rusitec, the molar proportion of acetate was similar between treatments on d 9 and 13, but was lower from d 10 to 12 and higher on d 14 to 16 with CIN than with control (interaction of treatment x sampling day). The molar proportion of acetate remained unaffected by CIN addition in the DF. In both CC systems, the molar proportion of propionate was decreased whereas that of butyrate was increased by CIN addition. In the DF, CIN decreased microbial N flow and efficiency of microbial protein synthesis. Protozoa numbers were lower with CIN than with control in both CC fermenters. In the Rusitec, CIN increased 15N enrichment in total bacterial fractions, but no effect was observed on the production of microbial N. This study showed that CIN exhibited antimicrobial activity in both CC systems, but the effects were more pronounced in the Rusitec than in the DF system. These differences are likely a reflection of the higher dilution rate in the DF resulting in a lower effective concentration of CIN than in Rusitec. Based on these changes in rumen microbial fermentation, supplementation of CIN at the concentration evaluated in this study may not be nutritionally beneficial to ruminants.

Pendred syndrome: evidence for genetic homogeneity and further refinement of linkage.

Pendred syndrome is the association between congenital sensorineural deafness and goitre. The disorder is characterised by the incomplete discharge of radioiodide from a primed thyroid following perchlorate challenge. However, the molecular basis of the association between hearing loss and a defect in organification of iodide remains unclear. Pendred syndrome is inherited as an autosomal recessive trait and has recently been mapped to 7q31 coincident with the non-syndromic deafness locus DFNB4. To define the critical linkage interval for Pendred syndrome we have studied five kindreds, each with members affected by Pendred syndrome. All families support linkage to the chromosome 7 region, defined by the microsatellite markers D7S501-D7S523. Detailed haplotype analysis refines the Pendred syndrome linkage interval to a region flanked by the marker loci D7S501 and D7S525, separated by a genetic distance estimated to be 2.5 cM. As potential candidate genes have as yet not been mapped to this interval, these data will contribute to a positional cloning approach for the identification of the Pendred syndrome gene.

Effects of antenatal diagnosis and selective abortion on frequencies of genetic disorders.

The total public health impact on the frequency of chromosomal disorders using maternal age cut-offs for amniocentesis is relatively small even if all pregnant women beyond 35 years of age were to have amniocentesis. Present-day reporductive practices would only permit the detection of about 20 per cent of cases of Down's syndrome in this age group. Methods to detect chromosomally abnormal fetal cells in maternal blood have much promise for the identification of all women carrying fetuses with abnormal chromosomes. Intrauterine diagnosis of most autosomal dominant disorders is currently not possible. Only relatively frequent autosomal recessive diseases for which simple techniques of heterozygote detection and fetal diagnosis of affected homozygotes are available can be significantly reduced in frequency by intrauterine diagnosis and selective abortion. Only Tay-Sachs disease currently meets these specifications. The paradoxical effect of increasing the frequency of the gene responsible for a disorder such as Tay-Sachs disease following abortion of affected fetuses is discussed but is considered negligible for many generations. Antenatal diagnosis of neural tube defects by assay of amniotic fluid alpha-fetoprotein when carried out following birth of an affected infant in the mother or in an immediate family member has only a small impact on the frequency of this condition. Blood screening for alpha-fetoprotein followed by confirmatory tests potentially can detect a large fraction of affected infants but many logistical problems of false positive and negative results remain. Reduction in the frequency of other multifactorial birth defects by the intrauterine diagnostic approach will require new methods based on blood screening of pregnant women. While the total present impact of antenatal diagnosis on the population frequency of all genetic disorders and birth defects is modest, the usefulness of the procedure in preventing various genetic diseases in families with previously affected members is great and should not be underestimated.

Superoxide dismutase variants in Newfoundland--a gene from Scandinavia?

An electrophoretic survey of variant red cell enzyme phenotypes in an isolated community in Newfoundland gave gene frequencies in marked contrast to those found in the capital, St. John's. In particular, a variant of red cell superoxide dismutase (SOD) gave a high variant frequency. Possible origins of the variant SOD allele are discussed.

Common variable immunodeficiency, Hodgkin's disease, and other malignancies in a Newfoundland family.

A large inbred family is described in which there were seven cases of Hodgkin's disease, three of lymphosarcoma, two of thymoma, two of common variable immunodeficiency, and single cases of retinoblastoma, neuroblastoma, and rhabdomyosarcoma. There have been no other lymphoma cases in the community during the past decade. Further study of this family may help to define the genetic basis for development of Hodgkin's disease and other disorders.