Discrepancies among the metaphase, telophase, and the G0/G1 and G2 DNA peaks of heteroploid cell lines

Heteroploid cell populations often show narrow peaks of G0/G1 and G2/M DNA content and broadly distributed chromosome numbers. This was originally explained by the selective metaphase arrest of the cells that have non-modal chromosome numbers. To test whether this explanation applies, we have measured the chromosome number distributions, as well as the G0/G1, G2, metaphase (M), and telophase (T) DNA distributions, of the cell lines WCHE-5, MCa-11, and HL-60. The WCHE-5 cells had narrowly distributed chromosome numbers and G0/G1 G2, M, and T DNA peaks. The MCa-11 and HL-60 cells also had narrowly distributed G0/G1 and G2 DNA peaks, but broadly distributed chromosome numbers and M and T DNA peaks. The widths of the MCa-11 and HL-60 M- and T-cell DNA peaks were similar to those of their chromosome number peaks, suggesting that all cells were completing mitosis, regardless of chromosome number or DNA content. Thus, selective metaphase arrest does not seem to be the cause of the narrow G0/G1 and G2 DNA peaks of heteroploid cell populations.     

Low level of Hox1.3 gene expression does not preclude the use of promoterless vectors to generate a targeted gene disruption. off.

A variety of experimental approaches have been devised recently to mutate mammalian genes by homologous recombination. In this report, we describe the disruption of the Hox1.3 locus by using two of these approaches, namely, positive-negative selection and activation of a promoterless gene. Interestingly, we observe similarly high frequencies of targeted disruption with both procedures. The high frequency of targeted disruption with a promoterless vector was unexpected given the extremely low level of Hox1.3 expression in the embryonic stem cell line used for these studies. These data indicate that minimal expression of the target gene is required to enrich for homologous recombination events with promoterless vectors and thus enhance the promoterless gene approach as a general strategy to mutate mammalian genes by homologous recombination.     

Transmission electron microscopical studies of the site of attachment of Ancylostoma ceylanicum to the small bowel mucosa of the dog

The host-parasite interaction at the site of attachment of the adult hookworm, Ancylostoma ceylanicum, to the small bowel mucosa of the dog has been examined by transmission electron microscopy. The lamina propria around the heads of the worms showed intense infiltration with neutrophilic and eosinophilic leucocytes, and plasma cells were also prominent. Erythrocytes were extravasated within the lamina propria while the portions of mucosa engulfed into the buccal cavities of the worms were necrotic and included aggregates of collagen fibres. Within the lumina of the worms were erythrocytes in varying stages of lysis together with other necrotic debris. The mucous membrane adjacent to the heads of the worms was ulcerated while more distant enterocytes were small, distorted and displayed various degrees of microvillar loss. Many mucosal blood vessels had platelet aggregates within their lumina but no fibrin deposition was observed. Vessels were often seen in the bases of the ulcers and were prone to rupture. Erythrocytes and leucocytes were seen in the dog intestinal lumen in close proximity to the bodies of the worms.     

Impact of the Brain Death Ruling in Washington State

In a 1980 Washington State Supreme Court decision, brain death was recognized as a means of determining death, but the court declined to specify a procedural mechanism to be followed. According to a survey of hospitals in Washington, the decision has had little impact in the state, apparently due to the medical profession''s unfamiliarity with it. As a result of the survey, we have identified problems of procedure and interaction with the legal system. A consensus of those contacted was that no formal, hospital-mandated definition of brain death is needed.     

Deviations from Hardy-Weinberg Proportions: Sampling Variances and Use in Estimation of Inbreeding Coefficients

An analysis is made of the distribution of deviations from Hardy-Weinberg proportions with k alleles and of estimates of inbreeding coefficients (f) obtained from these deviations.—If f is small, the best estimate of f in large samples is shown to be 2Σ _i(T_ii/N_i)/(k - 1), where T_ii is an unbiased measure of the excess of the ith homozygote and N_i the number of the ith allele in the sample [frequency = N_i/(2N)]. No extra information is obtained from the T_ij, where these are departures of numbers of heterozygotes from expectation. Alternatively, the best estimator can be computed from the T_ij, ignoring the T_ii. Also (1) the variance of the estimate of f equals 1/(N(k - 1)) when all individuals in the sample are unrelated, and the test for f = 0 with 1 d.f. is given by the ratio of the estimate to its standard error; (2) the variance is reduced if some alleles are rare; and (3) if the sample consists of full-sib families of size n, the variance is increased by a proportion (n - 1)/4 but is not increased by a half-sib relationship.—If f is not small, the structure of the population is of critical importance. (1) If the inbreeding is due to a proportion of inbred matings in an otherwise random-breeding population, f as determined from homozygote excess is the same for all genes and expressions are given for its sampling variance. (2) If the homozygote excess is due to population admixture, f is not the same for all genes. The above estimator is probably close to the best for all f values.     

Fatty acid control of cyclic AMP levels inNeurospora crassa

Several saturated, monosaturated, and polyunsaturated fatty acids produce rapid increases in cyclic AMP levels in the fungusNeurospora crassa when added to the growth medium at 10–50 M. The time courses of cyclic AMP increase resembled those previously shown to be induced by other agents, reaching peak cyclic AMP levels at about 2 min after fatty acid addition. These fatty acids had little or no influence on adenylate cyclase fromNeurospora crassa in vitro. On the basis of previous evidence that uncouplers of oxidative phosphorylation increase cyclic AMP levels and that fatty acids can act as uncouplers, we suggest that the fatty acids in vivo may act to increase cyclic AMP levels by acting as uncouplers of oxidative phosphorylation. In agreement with this suggestion, two fatty acids were shown to produce decreased ATP-ADP ratios inNeurospora at concentrations producing cyclic AMP increases.     

Malignant hypertension in women of childbearing age and its relation to the contraceptive pill.

Eleven of 34 women aged 15-44 with malignant phase hypertension were taking oral contraceptives at presentation. All had had normal blood pressure before starting to take the pill. In four the interval between the start of oral contraception and the diagnosis of malignant hypertension was less than four months, and in eight no other cause for the hypertension was found. Underlying renal disease and renal failure were less common among pill users than among non-users with malignant hypertension who were of similar age. No pill user became normotensive after withdrawal of the pill, but blood pressure was well controlled (diastolic less than 90 mm Hg) in three patients taking only one drug. By contrast, all 23 non-users needed two or more antihypertensive drugs to control blood pressure. Ten year survival was 90% among pill users and 50% among non-users. These results suggest that oral contraceptives may be a common cause of malignant hypertension in women of child-bearing age. If the pill is stopped and underlying renal disease excluded the long term prognosis for such patients is excellent.     

GABA-like immunoreactivity of identified interneurons in the flight system of the locust,Locusta migratoria

Summary The transmitter content of identified inhibitory interneurons in the flight system of the locust, Locusta migratoria, has been characterized using antibodies raised against protein-conjugated gamma aminobutyric acid. Identified flight neurons were filled with the fluorescent dye, Lucifer Yellow. Serial sections of dye-filled neurons were incubated with an antibody to gamma aminobutyric acid which was subsequently tagged with a fluorescent marker. Excitatory motoneurons to wing muscles and 13 flight interneurons (3 excitatory, 7 inhibitory, and 3 with unknown synaptic effect) were examined. Neither the moto-neurons nor any of the 3 excitatory interneurons contained immunoreactive material. Six of the 7 inhibitory interneurons did contain immunoreactive material. All the neurons which contained immunoreactive material and whose synaptic effect is known were inhibitory. We conclude that most of the inhibitory flight interneurons which have been described use gamma aminobutyric acid as their transmitter. Interestingly, at least 1 set of interneurons known to be inhibitory does not use gamma aminobutyric acid. We predict that the 2 interneurons which do contain immunoreactive material and whose synaptic effect is not yet known will be found to have inhibitory roles in the operation of the flight circuitry.