The nature of X-ray-induced mutations in mature sperm and spermatogonial cells of Drosophila melanogaster.

Mutations at four X-linked visible loci (yellow, white, vermilion and forked) induced by X-irradiation of mature sperm and spermatogonial cells were analysed genetically and cytogenetically. In addition, a fraction of the intragenic vermilion mutations was analysed molecularly. Males of two wild-type strains (Amherst M56i and Berlin-K) were used. A total of 332,651 chromosomes of irradiated mature sperm and 311,567 of irradiated spermatogonial cells were scored. The ratio of F1 female sterile, F2 male lethal and F2 male viable mutations in mature sperm and spermatogonial cells is very similar. The cytogenetic analysis shows equal fractions of multilocus deletions and translocations among the mutations recovered from both stages of spermatogenesis. These data strongly suggest that the spectrum of X-ray mutations is similar in mature sperm and spermatogonial cells, including multilocus deletions and chromosome rearrangements. The molecular analysis of a number of intragenic vermilion mutations showed the presence of three small deletions (1-10 bp), one insertion of two nucleotides and seven single nucleotide changes.

Characterization of MR (P) strains of Drosophila melanogaster: the number of intact P elements and their genetic effect.

To study the effect of mutagenic/carcinogenic agents on P-element transposition, the P strains used should be defined, especially with respect to the number of intact and functional P elements present. In this investigation, the relation between the number of complete P elements present in dysgenic males and P-insertion mutagenesis was studied in several MR (P) strains. The main conclusions from this investigation are: (1) Complete P elements can be present in the genome without genetic activity (even in a 'dysgenic' cross). As a consequence, the number of complete P elements present in particular dysgenic flies, is not necessarily an indication of their dysgenic genetic activity. (2) The MR-h12/Cy strain carries two complete P elements, one on the X chromosome without and one on the MR chromosome with genetic activity (making this strain most suitable for studies on P-transposition mechanisms).

The cervical spine in hemophilia.

Fifty-three patients with known hemophilia A or B were retrospectively reviewed to determine the incidence of cervical spine involvement. Twenty-five were examined prospectively, including a detailed history and physical examination and cervical spine roentgenograms consisting of an AP and lateral flexion-extension series. All roentgenograms were reviewed by a board-certified radiologist. The mean age of patients in both groups was 25.4 years (range, eight to 54 years). In the retrospective review, no patients were noted to have complaints referable to the cervical spine, although five patients had prior trauma to the cervical spine. In the prospective study, 8 of 25 patients complained of intermittent neck discomfort and 9 of 25 had restricted lateral rotation and/or lateral flexion. No patient had radicular symptoms or objective neurologic deficits. Roentgenograms showed abnormalities in 13 of 25 patients. Ten patients (aged 19 to 54 years; mean, 32 years) showed cystic changes or endplate irregularity within one or more vertebral bodies. Two patients, aged 15 to 19 years, had an increased atlanto-dens interval of 5 mm (normal, 3 mm). No odontoid erosion was noted. No correlation was found between the severity of peripheral involvement and the cervical spine roentgenograms. Occult instability of the cervical spine is discussed, along with ramifications for patients with hemophilia.

The indications for metrizamide myelography. Relationship with complications after myelography.

To test the validity of our impression that in the absence of objective clinical evidence of nerve-root impingement there is a disproportionately high incidence of complications associated with myelography, the results in 248 patients were reviewed retrospectively and those in 110 were studied prospectively. Of all 358 patients, 53 per cent had complications after myelography with injection of metrizamide, of which headache and nausea and vomiting were the most frequent. The incidence of complications in the 112 patients whose objective clinical and myelographic findings were consistent was compared with that in the 180 patients who had only subjective complaints and normal myelographic findings. The incidence of complications was 30 per cent in the former group and 70 per cent in the latter group, an almost twofold difference (p greater than 0.05). The 110 patients in the prospective study were asked to grade the intensity of their headache after myelography. Of the thirty-one patients with positive objective clinical and myelographic findings, ten complained of headache, which was mild in seven (70 per cent) and severe in three. Of the sixty patients with only subjective complaints, thirty-eight complained of headache, which was mild in twelve (32 per cent) and severe in twenty-six.