Chiasma derived genetic maps and recombination fractions: chromosome 1

Chiasma distribution data from six human males have been used to calculate genetic distance and recombination fraction for chromosome 1. Estimates given for each major chromosome band are valid only under the assumption that there is no chromatid interference, no chiasma movement, and no differential chromosome contraction between mitosis and meiosis.     

An Improved Technique for the Internal Mammary Artery Coronary Bypass Graft Procedure

An improved technique for internal mammary artery graft preparation is described. Following cautery dissection of the internal mammary artery (IMA) pedicle, the pedicle investing fascia is incised to the adventitial level along a single plane. This incision allows the tissue around the internal mammary artery to fall away and severs the muscular constrictions that often surround the internal mammary artery. Balloon calibration is performed to identify remaining constrictions and to relieve internal mammary artery spasm. A shear force limiting gauge insures that the exerted balloon force remains below the level demonstrated to cause intimal damage during electron microscopic studies. This technique allows full internal mammary artery distention without the devascularizing effects of full skeletonization. Distention of the distal internal mammary artery provides an enlarged hood to facilitate suture placement. Elongation of the internal mammary artery during balloon calibration aids in the performance of sequential grafts. This technique has been applied to 793 patients over the past five years. Postcalibration flow rates increased 3- to 18-fold over precalibration flow rates. Two early occlusions occurred during this series, one due to endothelial strippage prior to the development and use of the shear force limiting gauge. Follow-up showed 93.3% of patients to be asymptomatic. This combination of fascial incision and balloon calibration appears to offer safe technical and functional improvements to the performance of the internal mammary artery graft.     

Chiasma derived genetic lengths and recombination fractions: a 46, XY, t(9; 10) (p22; q24) reciprocal translocation

Chiasma distribution data on chromosomes 1, 2 and 9 from a reciprocal translocation carrier with a 46, XY, t(9; 10) (p22; q24) karyotype were used to calculate genetic distances and recombination fractions for chromosome segments corresponding to the major mitotic bands and for intervals between the centromeres and points at 10% intervals along the chromosome arms. These values were compared with those from control males with normal karyotypes. The translocation showed a marked increase in crossing-over in one specific region of chromosome 9 and, in addition, there was evidence of interchromosomal effects in chromosomes 1 and 2.     

Chronic liver disease in children on long-term parenteral nutrition

Use of long-term total parenteral nutrition (TPN) is often presumed to be associated with serious hepatic dysfunction. In this retrospective study, we reviewed the complete charts of patients who had received TPN for more than 2.5 years, starting in infancy or childhood, for evidence of liver dysfunction. There were 16 male and 10 female patients with a total of 254.5 patient years on TPN. Seventeen patients have been on TPN since birth or early infancy. Thirteen of 26 patients derive ≥90% of their calorie intake from TPN. Six patients had hepatomegaly; two of them also had splenomegaly. Twenty-one patients had normal transaminases, nine have had past episodes of raised enzymes ranging from 2.5 to 7.5 times normal. Seventeen patients always had normal bilirubin levels, five had past episodes of hyperbilirubinaemia, while four patients had persistently raised bilirubin levels (range 1.5–20.7 g/dL). Alkaline phosphatase was normal for age in all patients except two. Hepatic synthetic function, as measured by albumin, pre-albumin levels and prothrombin time, was within the normal range in all patients except one. Liver biopsies were performed in eight patients. Two biopsies showed cirrhosis, one showed chronic active hepatitis (CAH) with cholestasis, two patients had fibrosis, one showed cholestasis and two biopsies were normal. One patient with cirrhosis and one with CAH were positive for hepatitis C antibody. Another asymptomatic patient was positive for hepatitis B. Only the patient with CAH had hepatic decompensation. We conclude that clinical hepatic failure is uncommon in our group of patients on long-term TPN for 2.5 years or more. Cirrhosis and fibrosis, when found, could not be solely attributed to TPN.     

Soil Nutrient-Vegetation Relationships in the Eden Area,N.S.W. II. Vegetation-Soil Associations

A soil survey in the forests of the Eden area, N.S.W., included the recording of the tree species present at each plot, and based on these data eight main vegetation types were classified. These vegetation associations have been assessed in relation to soil nutrient levels, elevations and topographical features. Elevation and soil fertility were the two main measured parameters which appeared to determine the association distribution but other factors, such as aspect and slope were important on specific sites. It has been concluded that the forest mosaics of this area can be related to readily measurable soil and environmental parameters but that further detailed studies beyond this general survey are required for verification.     

Preimplantation genetic diagnosis for hemophilia A using indirect linkage analysis and direct genotyping approaches

Summary. Background: Preimplantation genetic diagnosis (PGD) is an appealing option for couples at risk of having a child with hemophilia A (HA). Although many clinics offer PGD for HA by gender selection, an approach that detects the presence of the underlying F8 mutation has several advantages. Objectives: To develop and validate analysis protocols combining indirect and direct methods for identifying F8 mutations in single cells, and to apply these protocols clinically for PGD. Methods: A panel of microsatellite markers in linkage disequilibrium with F8 were validated for single‐cell multiplex polymerase chain reaction. For point mutations, a primer extension genotyping assay was included in the multiplex. Amplification efficiency was evaluated using buccal cells and blastomeres. Four clinical PGD analyses were performed, for two families. Results: Across all validation experiments and the clinical PGD cases, approximately 80% of cells were successfully genotyped. Following one of the PGD cycles, healthy twins were born to a woman who carries the F8 intron 22 inversion. The PGD analysis for the other family was complicated by possible germline mosaicism associated with a de novo F8 mutation, and no pregnancy was achieved. Conclusions: PGD for the F8 intron 22 inversion using microsatellite linkage analysis was validated by the birth of healthy twins to one of the couples. The other family’s situation highlighted the complexities associated with de novo mutations, and possible germline mosaicism. As many cases of HA result from de novo mutations, these factors must be considered when assessing the reproductive options for such families.     

Maternal Attachment in Primiparas

This paper describes a process used by primiparous mothers to develop a bond with their infants during the neonatal period. A conceptual framework describing how the process operates is derived from data collected by interview and by observation of mother-infant dyads. The mother goes through a discovery process which is activated at the time of birth by her infant's presence and a feeling of disbelief, which operates to motivate the mother to establish the identity of this stranger. The means as well us the forms of discovery vary over time. As u result of these discoveries, positive feelings toward her child are generated and reinforced. The process can be inhibited or facilitated by several factors operating in the environment and/or originating with the mother. implications for nursing care as well as avenues for future research are discussed.