The distribution of posterior parietal fibers in the corpus callosum of the rhesus monkey

Summary The distribution of posterior parietal fibers in the corpus callosum of the rhesus monkey was analyzed using autoradiographic techniques. Posterior parietal fibers are located in the posterior half of the body of the corpus callosum. There is some segregation of fibers with respect to their place of origin within the posterior parietal lobe. However, there is also overlap, particularly between fibers coming from the caudal inferior parietal lobule and the medial parietal lobe.Supported by the Veterans Administration, Edith Nourse Rogers Memorial Veterans Hospital, Bedford, Massachusetts and N.I.H. Grants NS 09211 and NS 16841     

Life expectancy in British Marfan syndrome populations

A total of 206 patients with Marfan syndrome were ascertained throughout genetic clinics in Wales and Scotland during the period 1970–1990. There were 45 deaths representing 22% of the cohort. Mean age at death was 45.3 ± 16.5 years. 50% median cumulative survival in the total cohort (n = 206) was 53 years for males and 72 years for females. Multivariate analysis confirmed severity as the best independent indicator of survival. These findings and survival curves will assist in the counselling of British families and individuals with Marfan syndrome.     

Dosimetry characterization of 32P catheter-based vascular brachytherapy source wire

Dosimetry measurements and Monte Carlo simulations for a catheter-based 32P endovascular brachytherapy source wire are described. The measured dose rates were obtained using both radiochromic dye film and an automated plastic scintillator. The investigated source has dimensions of 27 mm in length and 0.24 mm in diameter, and is encapsulated in NiTi. For the radiochromic film measurements, calibrated radiochromic dye film was irradiated at distances between 1 and 5 mm from the source axis in A-150 plastic, and read out with a high-resolution scanning densitometer. The depth-dose curve measured in A-150 is then converted to that in water using correction factors obtained from Monte Carlo calculations. For the scintillator system, direct measurements in water were acquired at distances between 1 and 6 mm from the center of the source, along the perpendicular bisector of the source axis. The scintillator was calibrated in terms of absorbed-dose rate in a reference beta-particle field at multiple depths. The measured dose rates obtained from the film and scintillator measurements were then normalized to the measured source activity, i.e., to convert the measured data to units of cGy/s/mCi. Theoretical dosimetry calculations of the catheter-based 32P wire geometry were also obtained from Monte Carlo simulations using the Electron Gamma Shower code (EGS4), the Monte Carlo N-particle transport code (MCNP4B), and CYLTRAN from the Integrated Tiger Series codes (ITS v.3) and found to be in good agreement. The results of both measurements and calculations are expressed as absorbed-dose rate in water per unit of contained activity (cGy/s/mCi). Comparisons indicate that the measured and calculated dosimetry are in good agreement (<10%) within the relevant treatment distances (1-5 mm). This work fully characterizes the radiation field around a novel 32P beta brachytherapy source in water. The depth-dose curve can be used to calculate the dose to the vessel wall from a 27 mm 32P source wire centered within the vessel lumen.     

Folate-related genes and omphalocele

Women who take folic acid in the periconceptional period greatly reduce their chances of having a child with a neural tube defect (NTD). Using multivitamins may also reduce the risk of having a child with an omphalocele. In this study, we tested single nucleotide polymorphisms in folate-related enzyme genes for association with omphalocele. Polymorphisms in methylenetetrahydrofolate reductase (MTHFR), methylenetetrahydrofolate dehydrogenase (MTHFD1), the reduced folate carrier (SLC19A1), and transcobalamin II (TCN2) were examined in 25 children with euploid omphalocele and 59 matched controls. Omphalocele cases were significantly more likely to carry the T allele of MTHFR 677C-->T, a known risk factor for NTDs (odds ratio 3.50, 95% confidence interval 1.07-11.47, P=0.035). The MTHFD1 R653Q, SLC19A1 R27H, and TCN2 P259R polymorphisms showed no significant association with omphalocele. In this small study, the thermolabile variant of MTHFR, 677C-->T, was associated with an increased risk for omphalocele. This variant causes reduced enzyme activity, thus suggesting a mechanism by which multivitamins with folic acid might prevent omphalocele. Additional investigation is required.     

Computed tomography of the hindfoot

This investigation used computed tomography (CT) to study the normal anatomy of the hindfoot and to demonstrate abnormalities in patients with rheumatoid arthritis, pes planovalgus , old trauma, and soft-tissue masses. The hindfeet of 10 normal volunteers and 17 patients were scanned in the coronal and axial transverse planes. The articular surfaces of the tibia, talus, and calcaneus were assessed, as were the relationships of each bone to the others. Normal subjects had markedly symmetrical hindfeet . The "heel valgus angle" (relating the calcaneus to the tibia) was 5.2 +/- 1.6 degrees (mean +/- standard error of the mean). The "sustentacular angle" (indicating the angle of elevation of the sustentaculum tali at the midsubtalar joint) was 18.3 +/- 1.3 degrees. The "medial offset" of the talar head with respect to the calcaneus (measured at the anterior subtalar joint) averaged 5.2 +/- 1.8 mm. Patients with rheumatoid arthritis had erosions involving both sides of the subtalar joint, leading to talocalcaneal alignment abnormalities. In patients with pes planovalgus the heel valgus angle was greater and the elevation of sustentaculum tali lower in the foot that was most severely affected. Bony talocalcaneal fusions, fractures, and the erosions of pigmented villonodular synovitis were detected on CT. The pattern of postoperative bone healing after attempted subtalar fusion could be demonstrated. We conclude that CT is a useful tool for pre- and postoperative evaluation of the hindfoot.     

Converging visual and somatic sensory cortical input to the intraparietal sulcus of the rhesus monkey

A cyto- and myeloarchitectonic study reveals the presence of a distinct cortical zone ("area POa") in the lower bank of the intraparietal sulcus of the rhesus monkey. Using both autoradiographic and silver impregnation techniques, an analysis of cortical connections shows two overlapping projections to this sulcal zone. These come from (1) the middle portion of the preoccipital gyrus (area OA) and (2) the rostral inferior parietal lobule (area PF).     

Laparoscopic excision of ovarian neoplasms subsequently found to be malignant.

One hundred fifty-six members and candidate members of the Society of Gynecologic Oncologists responded to a survey concerning the "laparoscopic management of ovarian neoplasms subsequently found to be malignant." Twenty-nine responders (19%) reported a total of 42 cases of ovarian malignancy. The laparoscopic procedure was aborted or the cyst was aspirated in 38% of the cases, and partial or complete excisions were attempted in 33 and 29%, respectively. The characteristics of the masses were as follows: less than 8 cm 67%, cystic 62%, unilocular 48%, and unilateral 81%. All four "benign" characteristics were present in 31% of the cases found to be malignant, and three of four characteristics were present in 24%. Laparotomy was performed at the time of laparoscopy in 17% of cases, after laparoscopy in 71% with an average interval of 4.8 weeks, and not at all in 12%. Fifty-seven percent of the cases were invasive epithelial malignancies, whereas 29% were tumors of low malignant potential. At least 50% of the patients had stages II-IV. We conclude that attempted laparoscopic excisions of adnexal masses that are subsequently found to be malignant are not uncommon, and that the presence of so-called "benign" characteristics does not preclude malignancy. Attempts at partial or complete excision are common, as are delays in subsequent definitive surgery. The stage of disease is often advanced, and all histologic types of malignancy are encountered. We advocate careful evaluation of this practice, with development of strict guidelines to ensure optimal patient care.     

妥卡尼对豚鼠心室肌细胞钙电流和钾电流的抑制作用

利用酶分散的成年豚鼠心室肌细胞和全细胞电压钳技术,研究了妥卡尼(tocainide)对心室肌细胞钙电流(I_ca)、延迟整流钾电流(I_k)和ATP敏感性钾电流(Ik,ATP)的作用。结果表明,妥卡尼对I_ca和I_k均显示浓度相关的抑制作用,妥卡尼50umol·L^-1对I_ca和I_k的抑制率分别为16%和3%。这可能是妥卡尼有效抑制室上性心动过速和缩短心肌动作电位平台期的重要机制。