Diplospermy II indicated as the origin of a liveborn human triploid (69,XXX).

A 69,XXX liveborn baby was shown to have the Rh genotype CDe/cDE/cde which suggested that 46 of her chromosomes were of paternal origin. Studies on C band polymorphisms and other genetic markers indicated that the most likely origin of this triploid was a failure of male meiosis II.

Human Y chromosome variation in normal and abnormal babies and their fathers.

C-banded chromosome preparations were obtained from cord blood from normal newborns and venous blood from abnormal newborns and the corresponding fathers. There is significant heterogeneity between individuals in euchromatin and especially heterochromatin lengths of the Y chromosome. The average dimensions of the Y of fathers of normal and abnormal babies do not differ. Y chromosomes from cord blood appear more condensed than from venous blood and the consequences are not removed by the use of the Y/F index. Such differences have not been considered in reported apparent variation in the size of the Y chromsome in relation to criminality.

Clonal evolution of marker chromosomes in a case of myelofibrosis with myeloid metaplasia and myeloblastic transformation.

The diverse spectrum of acquired chromosome abnormalities in a female patient with myelofibrosis and myeloid metaplasia is described. A sequence of karyotypic evolution involving a ring chromosome is postulated. The terminal clinical picture was unusual in that there was obstructive renal failure from extramedullary myeloblastic transformation and infiltration of the bladder, and this was also present in other sites. Initially neutrophils showed low alkaline phosphatases activity but latterly two distinct populations in which cells had either high activity or none.

Standardization of a rapid microbiologic assay for aminoglycosides using Enterobacter cloacae.

The standardization of a rapid serum aminoglycoside assay using Enterobacter cloacae is described. This includes the sensitivity testing of the organism and its performance on various media, with Mueller-Hinton agar being the medium of choice. The precision and reproducibility of the assay, as measured by the within-run and between-run coefficients of variation, were 5.0 and 5.9, respectively. A significant positive correlation was obtained between the microbiologic assay for gentamicin and a 125I-labeled gentamicin radioimmunoassay with the use of both normal and uremic sera. When known amounts of gentamicin, tobramycin, and amikacin were added to antibiotic-free sera from normal persons, recovery rates of 80.0% to 97.9% were found. In the case of gentamicin, recovery rates of 85.0% to 97.9% were found with the use of sera from patients undergoing either hemodialysis or peritoneal dialysis. There were no effects on the recovery rates of the aminoglycosides from normal serum if high concentrations of clindamycin, methicillin, ampicillin, penicillin G, cephalothin, cefamandole or cefoxitin were also present in the sera. The newer cephalosporins, cefamandole and cefoxitin, had no in-vitro effect on the Kirby-Bauer sensitivity patterns of gentamicin, tobramycin, or amikacin, when tested against the assay organism.

Reciprocal translocation and the Philadelphia chromosome.

We examined metaphases from three patients with chronic myeloid leukaemia and a typical Philadelphia chromosome with one chromosome 9 as the recipient to determine whether the 9q+22q- translocation is reciprocal. Good quality G-banded photographs of the chromosomes concerned were subjected to light absorption density analysis. This provided enlarged tracings corresponding to the relevant chromosome regions and so facilitated accurate measurement. This technique has unambiguously shown that the typical Philadelphia chromosome results from a reciprocal translocation and that probably no material is gained or lost in the exchange. Furthermorein a total of six patients for whom sequential G and C banding was performed, the chromosome 9 with the largest block of centromeric heterochromatin received the translocated material. We offer tentative explanations for this curious observation.

Familial erythroleukaemia: a cytogenetic and haematological study.

Clinical and haematological details of 2 siblings with a familial myeloproliferative disorder (erythroleukaemia) are presented. Their father is presumed to have died from a similar disease. The 2 siblings showed similar but not identical chromosomal abnormalities detected initially in marrow and later in peripheral blood. Serial studies revealed the emergence of an increasingly diverse pattern of chromosomal changes coincident with the haematological and clinical progression of the disease. Other members of the family were screened for cytogenetic and haematological changes. The paternal sibship displayed an increased incidence of cancer.

Cytogenetic study of 10 cases of infectious mononucleosis.

Cytogenetic analysis of 10 cases of infectious mononucleosis has revealed increased damage in the form of chromosome breakage and aberrations typical of viral infection, but in addition a few cells were consistently found to harbour a deleted number 22, similar tsponse to the mitogen phytohaemagglutinin is suggested. This inhibitor appears to have a reversible action on the patient's own lymphocytes but no inhibitory effect on control lymphocytes.

Variation in the Philadelphia chromosome.

Cytogenetic study of 17 cases of chronic myeloid leukaemia has shown that the Philadelphia chromosome is a variable entity, differing in size and banding pattern between individuals.

Age trends in human chiasma frequencies and recombination fractions. I. Chiasma frequencies.

Chiasma frequency data on 183 males were subjected to an analysis of covariance. There appeared to be little or no linear trend in chiasma frequency with age. This conclusion was supported by a detailed analysis of chiasma frequencies for each autosome from 21 males. There were, however, significant differences among investigators in reported mean chiasma frequencies.