Maximum likelihood estimation by counting methods under polygenic and mixed models in human pedigrees.

For pedigree data, the maximum likelihood estimates of the parameters in polygenic and mixed models are derived analytically although not in closed form but in terms of "counting equations" allowing an iterative solution. Likelihood computations, tests of significance, and tests of goodness of fit are presented. Accelerating the (linear) rate of convergence by a very simple method is demonstrated.     

Wound complications after median sternotomy: A study of 61 patients from a consecutive series of 9,279

Among a consecutive series of 9,279 sternotomies performed during a period of 2(1/2) years, 61 (0.66%) patients developed significant wound complications. Of these, 58 (95.1%) survived. Sternal infection occurred in 36 patients (0.39%). Predisposing factors included chronic obstructive pulmonary disease, diabetes mellitus, obesity, closed chest massage, prolonged assisted ventilation, and excessive bleeding after operation. Positive end expiratory pressure (PEEP) did not, in itself, predispose to sternal dehiscence. Intermittent positive pressure breathing (IPPB) treatments caused excessive coughing, which may have increased the likelihood of dehiscence. Disposable drapes and expeditious surgery probably contributed to the low incidence of wound infection. Early diagnosis, surgical debridement, rewiring and primary closure with substernal drainage, without continuous antibiotic irrigation, resulted in satisfactory resolution in most patients.     

Ionescu-Shiley pericardial xenograft valve: Hemodynamic evaluation and early clinical follow-up of 326 patients

Dissatisfaction with the hemodynamic characteristics of available porcine valves prompted a clinical trial of the Ionescu-Shiley percardial xenograft (ISPX) valve. Three hundred fifty-six ISPX valves were implanted consecutively in 326 patients. Operative mortality was 2.6% (2/75) for aortic valve replacement alone and 7.7% (12/155) for aortic valve replacements that included reoperations and combined procedures such as mitral commissurotomy, annuloplasty, and coronary artery bypass. Operative mortality for all patients who underwent mitral valve replacement was 9.5% (14/147). The mean peak systolic gradient pressure in the aortic position was 5.4 mm Hg overall and 4.27 mm Hg with the size 19 mm valve. There were no embolic episodes in patients who received the ISPX valve in the aortic position. The available data indicate that the rate of peripheral embolism with the ISPX valve compares favorably with that of porcine valves. Considering its hemodynamic advantage, if the longterm durability of the full-orifice Ionescu-Shiley pericardial xenograft valve continues to be confirmed by follow-up studies, it is our opinion that it is the biologic valve of choice.     

Breeding soundness examinations of rams and bucks, a review

Breeding soundness examinations of rams and bucks may be performed by veterinarians as a service for clients. A physical examination for breeding soudness includes a general examination for health with special consideration of the reproductive organs. Careful examination of the penis, prepuce, and testicles may reveal diseases or abnormalities which decrease reproductive potential. Rams with small or hypoplastic testicles are unsatisfactory potential breeders as testicle size is positively related to sperm production. Libido may be assessed during semen collection procedures or from observations of the owner. Semen quality may be evaluated using tests for motility, concentration, and morphology of spermatozoa. Rams may be declared satisfactory, questionable, or unsatisfactory potential breeders as a result of the examination.     

The septo-hippocampal pathway: electrophysiological observations

In 40 rats immobilized with gallamine evoked field potentials were elicited in the dorsal hippocampus by stimulation of the septal nuclei. Latency of the septohippocampal evoked potential (SHEP) elicited by stimulation of the medial septal nuclei, the variations of latencies and amplitudes with increasing stimulus intensities as well as the occurrence of frequency potentiation and post-tetanic potentiation allow the conclusion that the SHEP registered in the stratum granulare of dentate gyrus is mainly monosynaptically elicited. Nevertheless some data discussed in the paper point to the existence of a more complicated and not exclusively monosynaptic activation of granular cells caused by septal stimulation.     

Preparative size-exclusion chromatography of human serum apolipoproteins using an analytical liquid chromatograph

Apolipoproteins, extracted from human serum high-density lipoproteins, can be resolved and recovered with high yield from a preparative MicroPak TSK Type 3000SW size-exclusion column using Tris-buffered 6 m urea or 6 m guanidinium chloride mobile phases. Adequate resolution of some apolipoprotein pairs is only achieved at low flow velocities and low sample loads, necessitating repetitive injections of small amounts of material for preparative isolation. An analytical high-performance liquid chromatograph equipped with a simplified sample introduction scheme and low-pressure switching valves for fraction collection was used to isolate milligram quantities of HDL apolipoproteins.     

Transport of organic cations by a renal epithelial cell line (OK)

The goal of this study was to determine the mechanisms involved in the transport of the organic cation, tetraethylammonium (TEA), across the apical membrane of OK cells. [14C]TEA accumulated in OK cell monolayers reaching equilibrium in 2 h. The uptake of [14C]TEA at equilibrium was dependent upon temperature and was inhibited by sodium azide and by various organic cations, including N1-methylnicotinamide (NMN), mepiperphenidol, and cimetidine but not by the organic anion, p-aminohippuric acid. The initial uptake of [14C]TEA was characterized by a saturable process. The mean +/- S.D. Km was 27.8 +/- 2.6 microM and the Vmax was 414 +/- 26.5 pmol/mg protein/min. Both an accelerated efflux and influx of [14C]TEA in the presence of a trans-gradient of unlabeled TEA and NMN was observed, whereas a deaccelerated influx and efflux was observed in the presence of a trans-gradient of mepiperphenidol. The mechanism of interaction between NMN and TEA was examined. NMN significantly increased the apparent Km (mean +/- S.D.) of TEA to 82.8 +/- 16.4 microM (p less than 0.001), whereas the Vmax (mean +/- S.D.) was only slightly affected (478 +/- 72 pmol/mg protein/min) suggesting a competitive inhibition. The stimulatory effect of trans-gradients of NMN on TEA transport was due to an increase in the Vmax of TEA suggesting that NMN trans-stimulates TEA transport by increasing the turnover rate of the exchanger. In the presence of an inwardly directed proton gradient, the efflux at 30 s of [14C]TEA from the OK cell monolayers was significantly accelerated (p less than 0.05). Studies with the pH-sensitive fluorescent probe, 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein, suggested that TEA could drive the countertransport of protons. In apical membrane vesicles prepared from OK cells, the uptake of [3H]NMN exhibited an apparent "overshoot phenomenon" in the presence of an initial outwardly directed proton gradient. Protons competitively inhibited TEA uptake suggesting that the proton/organic cation and the organic cation/organic cation self exchange mechanism are the same mechanism. This is the first report describing both TEA self-exchange and proton/TEA exchange in the apical membrane of a continuous cell line. OK cells are an excellent model for the study of organic cation transport across the apical membrane.     

Basis for receptor specificity of nonecotropic murine leukemia virus surface glycoprotein gp70SU.

Murine leukemia viruses (MuLVs) initiate infection of NIH 3T3 cells by binding of the viral envelope (Env) protein to a cell surface receptor. Interference assays have shown that MuLVs can be divided into four groups, each using a distinct receptor: ecotropic, polytropic, amphotropic, and 10A1. In this study, we have attempted to map the determinants within viral Env proteins by constructing chimeric env genes. Chimeras were made in all six pairwise combinations between Moloney MCF (a polytropic MuLV), amphotropic MuLV, and 10A1, using a conserved EcoRI site in the middle of the Env coding region. The receptor specificity of each chimera was determined by using an interference assay. We found that amphotropic receptor specificity of each chimera was determined by using an interference assay. We found that amphotropic receptor specificity seems to map to the N-terminal portion of surface glycoprotein gp70SU. The difference between amphotropic and 10A1 receptor specificity can be attributed to one or more of only six amino acid differences in this region. Nearly all other cases showed evidence of interaction between Env domains in the generation of receptor specificity. Thus, a chimera composed exclusively of MCF and amphotropic sequences was found to exhibit 10A1 receptor specificity. None of the chimeras were able to infect cells by using the MCF receptor; however, two chimeras containing the C-terminal portion of MCF gp70SU could bind to this receptor, while they were able to infect cells via the amphotropic receptor. This result raises the possibility that receptor binding maps to the C-terminal portion of MCF gp70SU but requires MCF N-terminal sequences for a functional interaction with the MCF receptor.     

Effects of autoclave-induced carbohydrate hydrolysis on the growth ofBeta vulgaris cells in suspension

Media of de Greef & Jacobs (1979) were autoclaved either with all the nutrient components in a single vessel (medium 1) or with the following components in separate vessels: FeNa–EDTA+CaCl₂ (medium 2), FeNa–EDTA+NaH₂PO₄ (medium 3) or sucrose (medium 4). Medium 5 was prepared by autoclaving FeNa–EDTA+NaH₂PO₄ and sucrose in two separate vessels. It was found that the dry mass yield of cell suspensions ofBeta vulgaris was lowest in medium 1, followed by media 2 and 3. There was no significant difference among media 3, 4, and 5.The plot of dry mass yield of the cell suspensions against the rates of cyanide-initiated oxygen consumption which indicate the extent of carbohydrate hydrolysis of the media during autoclaving, indicated the presence of a threshold rate of about 17–20 nmol ml^–1 min^–1. Dry mass yield of the suspensions decreased rapidly when the rate exceeded this value.For media with glucose as the source of carbohydrate, the rate of cyanide-initiated oxygen consumption exceeded the threshold value by a factor of 1.5 to 2, depending on the volume of the media autoclaved.Abbreviations FeNa-EDTA ferric monosodium ethylenediamine-tetraacetic acid