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At least 37 records · Page 2Linked to original sources
PubMed1975

Mutagenic activity of cyclophosphamide, trofosfamide, and ifosfamide in drosophila melanogaster. specific induction of recessive lethals in the absence of detectable chromosome breakage.

The mutagenicity of cyclophosphamide (EndoxanR), trofosfamide (IxotenR), and ifosfamide was tested on male germ cells, mainly mature sperm, of Drosophila melanogaster. The genetic end points used were sex-linked recessive lethals, dominant lethals, sex chromosome loss, and partial Y chromosome loss. For recessive sex-linked lethals, all three substances induced a significant increase over the control. The effectiveness was not concentration dependent. None of the compounds induced dominant lethals, or complete or partial loss of the sex chromosome. The results are interpreted to indicate the existence of a rate-limiting factor which acts as restriction on the amount of active metabolite in the target cell. This amount is considered to be lower than that required to cause a detectable increase in chromosome breakage types of damage, but is detectable with the higher resolving power of the recessive lethal test.

Animals↗
PubMed1978

Molecular dosimetry of the mutagen ethyl methanesulfonate in Drosophila melanogaster spermatozoa: linear relation of DNA alkylation per sperm cell (dose) to sex-linked recessive lethals.

The dosage-response curve for EMS was determined with dose measured as ethylations of DNA per sperm cell, and response measured as the relative frequency of sex-linked recessive lethals induced in sperm cells of Drosophila melanogaster. Dose can be converted to ethylations per nucleotide of DNA by dividing ethylations of DNA per sperm cell by 3 X 10(8) nucleotides per sperm cell. Adult males were exposed to equal amounts of either [3H]EMS for determining dose or nonlabeled EMS for determining mutational response. By feeding EMS for 24 h in a concentration of 25 mM, a high dose of 1.4 X 10(-2) ethylations per nucleotide was observed. With 1.4% of the nucleotides ethylated, 57% of the X-chromosomes were hemizygously viable; therefore, ethylation per se is not very efficient in inducing mutations. The relative frequency of mutations increased linearly with the dose from a dose of 2.1 X 10(-4) to 1.4 X 10(-2) ethylations per nucleotide. No threshold was apparent, and the statistical limits of the exponent, 1.0 +/- 0.1, excluded an exponent as high as 1.2. This linear relation suggests no change in mechanism of mutagenesis occurs from low to high dose in Drosophila. A nonlinear relation was found between exposure and dose; when exposure was increased by a factor of 250 (from 0.1 to 25 mM EMS in the feeding medium) dose was increased by a factor of only 68. By extrapolating down from our lowest dose of 2.1 X 10(-4) ethylations per nucleotide with an observed frequency of 0.55% +/- 0.08% sex-linked recessive lethals, we estimate the doubling dose for sex-linked recessive lethals to be 4 X 10(-5) ethylations per nucleotide.

Alkylating Agents↗
PubMed1978

Dominant and recessive effects of induced-lethals in female mice by exposure to gamma-irradiation during the 10th to 14th day of intrauterine life.

The frequency of (dominant and) recessive lethal mutations induced by 160-rad chronic gamma-irradiation given with a dose rate of 0.03 rad/min during the 10th to 14th day of gestation has been studied in female CBA-mice. An increased rate of recessive lethal equivalents by about 10% has been noted. This increase corresponds to a mutation rate of 6.3 X 10(-4) mutation/rad/genome. There were not found any dominant mutations, nor any dominance effects from the induced recessive lethal equivalents. The hazards after irradiation during foetal development are discussed.

Animals↗
PubMed1979

Amelogenesis imperfecta among Israeli Jews and the description of a new type of local hypoplastic autosomal recessive amelogenesis imperfecta.

Amelogenesis imperfecta (AI) was detected in nine of 70,359 school children surveyed, a prevalence approximating 1:8,000. Of these cases, eight were the hypoplastic type and one the snow-capped hypomaturation type. Family studies demonstrated that hypoplastic AI was an autosomal dominant trait in two children and an autosomal recessive in six. Of three additional families referred to our clinic, two had autosomal recessive hypoplastic AI and one the hypocalcified type, inherited as an autosomal dominant trait. In four families, a new type of local hypoplastic autosomal recessive AI was observed, characterized by horizontal pitting and grooving more pronounced in the middle third of the crowns of most teeth in both dentitions.

Adolescent↗
PubMed1978

[The recessive Hm phenotypes].

The survival of "Bombay" erythrocytes as well as that of "para Bombay" red cells (first and third class according to Race and Sanger classification) has been studied among non compatible and "para Bombay" individuals. This shows not only the heterogeneity of these phenotypes (as already described by Salmon and co workers) but also the presence of highly differenciated ABH formed antigens. H deficient recessive phenotypes are not explained by the presence of an amorphe h gene. They arise from the activity (or better from the non activity) of the regulation genes of which the recessive alleles x and z in double dose do not enable a normal functioning of the H gene. The appelation Hxx for "Bombay" phenotypes (1st classe) and the appelation Hzz for Hm recessive (3d. class) phenotypes are proposed. Genetics as well as the synthesis of Ah, Bh (AHm, BHm) phenotypes have not yet been clarified. Interaction of zz and sese genes, or accomplementation in the "trans" position have to be looked at.

ABO Blood-Group System↗
PubMed1977

The timing of UV mutagenesis in yeast: a pedigree analysis of induced recessive mutation.

The mechanism of UV-induced mutation in eukaryotes was studied in individual yeast cells by a procedure that combined pedigree analysis and tetrad analysis. The technique involved the induction of recessive lethals and semilethals in G1 diploid cells. Induced frequencies were 25 and 61 percent at survival levels of 90 and 77 percent, respectively. No evidence of gross chromosome aberrations was detected. Recessive mutations that affect only one strand or that affect both strands of the DNA molecule are induced much at random among a population of cells, and both types can occur within the same cell. However, the data confirm that two-strand mutations are in the majority after a low level of irradiation. The simplest explanation involves a mechanism whereby most mutations are fixed in both strands prior to the first round of post-irradiation DNA replication. The recessive mutational consequences of irradiation are exhausted at the conclusion of the first post-irradiation cell division, although dominant-lethal sectoring continues at a high level through the second post-irradiation division. It is concluded that pyrimidine dimers that persist to the second round of DNA replication are rare or ineffective.

Cell Division↗
PubMed1977

Spontaneous and ethyl methanesulfonate-induced mutations controlling viability in Drosophila melanogaster. I. Recessive lethal mutations.

The efficiency of the adult feeding method for EMS treatment in Drosophila melanogaster was studied by measuring the frequency of induced recessive lethals on the second chromosome. The treatment was most effective when mature spermatozoa or spermatids were treated and was much less effective on earlier stages. The number of mutations induced was proportional to the concentration except at the highest doses. The recessive lethal rate was estimated to be about 0.012 per second chromosome per 10(-4) M. In addition, about 0.004-0.005 recessive lethals per 10(-4) M were found in a later generation in chromosomes that had not shown the lethal effect in the previous generation. When the experiments are done in a consistent manner and gametes treated as mature sperm or spermatids are sampled, the results are highly reproducible. However, modifications of the procedure, such as starvation before EMS treatment, can considerably alter the effectiveness of the mutagen.

Animals↗
PubMed1977

Adjustable rectus muscle recession surgery. A follow-up study.

Fifty-six patients underwent an adjustable rectus muscle recession procedure. This procedure permits the surgeon to enhance or diminish the amount of muscle recession on the evening after surgery or the first postoperative day if cover-testing indicates an inappropriate amount of undercorrection or overcorrection. The adjustable rectus muscle recession technique seems to be a practical and effective means to change the strabismic deviation postoperatively. The procedure requires patient cooperation and is most suitable for patients age 15 years and older. The procedure has been effective in altering the angle of deviation, and this alteration has been stable during the follow-up period in most cases. In this initial series, the reoperation rate was low, postoperative alignment was excellent, and complications were minimal.

Adolescent↗
PubMed1979

Autosomal recessive non-syndromal progressive sensorineural deafness in childhood. A separate clinical and genetic entity.

In a family with 11 children, three sibs (two boys and a girl) show progressive sensorineural deafness, first noticed at ages 4, 7 and 11, respectively. The progression of deafness was registered in each of these sibs over a period ranging from 9 to 15 years. The speech perception has simultaneously diminished, as observed also in the case of recruitment. The parents and the other sibs in this family have normal hearing. The parents were demonstrably consanguineous, and autosomal recessive transmission is therefore postulated. A syndromal diagnosis could not be established because general physical, neurological ophthalmological and haematological examination as well as urinalysis revealed no associated characteristics. A syphilitic infection was therefore also excluded as a possible cause. Pendred's syndrome was excluded by means of a potassium perchlorate test. It is believed that these three sibs are suffering from autosomal recessive non-syndromal progressive sensorineural deafness - a type of deafness hardly mentioned in the literature. Several authors differentiate this type of deafness from autosomal recessive early-onset neural deafness.

Adolescent↗
PubMed1978

Augmented recession of the medial recti.

Bimedial rectus recession with measurement from the limbus was combined with conjuctival recession 85 children undergoing surgery for esotropia. Using this augmented recession technique, the prism diopters of correction per millimeter of surgery done were 4.8 compared with 3.2 found in 56 control patients. Postoperatively, the conjunctiva had a satisfactory cosmetic appearance and ductions were normal.

Adolescent↗
PubMed1979

Recession: a 4-year longitudinal study after free gingival grafts.

Free gingival grafts were performed on recession areas around 42 teeth in 12 patients, with postoperative evaluation of recurrent recession after 1, 6, 12, 24 and 48 months. No changes in degree of recession were observed during the 4-year period. The vestibuloplasties, which were always wider than the transplants, exhibited recurrence up to the transplant margin 6 months after surgery, while the transplants themselves exhibited an average shrinkage of 25%. In addition, 25% of the increase in vestibular depth achieved by the surgery was lost 1 month postoperatively, but there was a tendency toward increasing vestibulum depth during the ensuing 47 months. Gingival sulcus depth was not affected by the surgery.

Follow-Up Studies↗
PubMed1978

Treatment of localized gingival recessions. Part I. Lateral sliding flap.

This study was undertaken to evaluate biometrically the changes that occur on the recipient as well as on the donor tooth with regard to gingival recession, sulcus depth and width of keratinized gingiva after performing a lateral sliding flap in the treatment of localized denuded roots. Fourteen teeth with gingival recession were treated using a lateral sliding flap. Measurements were recorded preoperatively and 1, 3 and 6 months after surgery. A mean gain of 2.69 mm of soft tissue coverage over the denuded root was found 6 months postoperatively which represents 69% of coverage. The mean gain in width of keratinized gingiva averaged 3.15 mm. On the donor tooth an average gingival recession of 1.1o mm was found after 6 months, and the width of keratinized gingiva decreased an average of 1.25 mm. Results remained stable after 30 days postsurgery.

Adult↗
PubMed1977

Changes in the activity of the ependyma in the infundibular recess of the brain of Rana esculenta L. in the annual cycle.

Volume of the cell nuclei of the ependyma of the infundibular recess was measured in 30 female and 30 male water frogs (Rana esculenta L.) obtained from their natural environment, taking into account the phase of the annual cycle. Karyometry of the ependymal cell nuclei in the infundibular recess in males and females showed statistically significant differences of volume (activity) in the annual cycle. The largest volume of nuclei of the ependymal cells in females and males was observed in the first decade of April (end of hibernation), and the smallest in the first decade of September (end of the period of active life). Activity of nuclei of cells from the infundibular recess clearly correlated with gonadal development.

Activity Cycles↗
PubMed1979

A scanning electron microscope study of the pineal recess of the adult brush-tailed possum (Trichosurus vulpecula).

The ventricular surface features of the pineal recess of 35 adult brush-tailed possums (Trichosurus vulpecula) were studied, mainly with the scanning microscope. The complex and interesting details observed have not been reported before. The pineal recess shows three distinct zones, and it is suggested that these be called: central, paracentral, and peripheral. The surface cells of the central zone show neither cilia nor microvilli, the paracentral zone shows microvilli (in a polygonal and homogeneous array), supraependymal cells and CSF-contacting nerve processes, while the peripheral zone is heavily ciliated. These features are consistent with the hypothesis that, in certain physiological states, the CSF from the pineal recess carrying pineal secretion is momentarily 'swept' forward in the direction of the median eminence to influence hypothalamic functions directly.

Age Factors↗
PubMed1978

Autosomal recessively inherited ocular albinism. A new form of ocular albinism affecting females as severely as males.

A new form of ocular albinism, autosomal recessively inherited ocular albinism (AROA), was studied in seven females and two males from five unrelated Caucasian kindreds. Affected patients have the impaired vision, translucent irides, congenital nystagmus, photophobia, albinotic fundi with hypoplasia of the fovea, and strabismus that are also found in X-linked ocular albinism (XOA). Unlike XOA, however, this form of ocular albinism is inherited as an autosomal recessive trait, with females affected as severely as males. Obligate heterozygotes of AROA lack the ocular abnormalities that are present in females heterozygous for XOA. Also, skin and hairbulb biopsy specimens do not reveal any abnormalities in patients with AROA, whereas giant pigment granules are found in patients heterozygous and hemizygous for XOA. The recognition of this disorder is imperative for proper diagnosis and responsible genetic counseling.

Adult↗
PubMed1977

Inbreeding in recessive diseases.

The consanguinity of parents (born in France) of individuals who have a recessive disease has been studied. The frequency of first cousin marriages is less than 0.2% in the general French population. Among the parents of affected individuals the following frequencies of first cousin matings were observed: cystic fibrosis: 1.4% cystinosis: 7.1% nephronophtisis: 5.6% spinal muscular atrophy: 4.5% albinism: 5.0% achromatopsia: 12.5% (Albinism and spinal muscular atrophy are heterogeneous conditions). The increase in the frequency of first cousin marriage relative to that of the general population is much greater, as expected, in cystinosis, which is a rare disease, than in cystic fibrosis, which is the most frequent recessive disorder in France. Inbreeding in cystinosis and cystic fibrosis was also studied by computing the distance between parental birth places. This distance is smaller in cystinosis than in cystic fibrosis.

Albinism↗
PubMed2026

Downbeat nystagmus without ataxia as an early manifestation of spinocerebellar ataxia, autosomal recessive type 10 (SCAR10): a case report.

The differential diagnosis of dizziness is broad and can include both vestibular and autonomic pathology. Vestibular dizziness is typically described as a sensation of movement (e.g. the world is spinning) while dizziness related to autonomic dysfunction is typically described as symptoms of orthostatic intolerance (e.g. postural lightheadedness). It is important to differentiate the type of dizziness to guide proper diagnostic and therapeutic workup. We describe the case of a young patient evaluated in the autonomic clinic for dizziness, ultimately found to have a rare cerebellar neurodegenerative disorder. A 23-year-old female with a past medical history of migraine without aura presented in autonomic clinic with a four-month history of slow, progressive onset of vestibular dizziness. Neurological exam was notable for downbeat nystagmus, but no appendicular or truncal ataxia was appreciated. Subsequent vestibular evaluation was consistent with central vestibular dysfunction. Magnetic resonance imaging (MRI) of the brain with and without contrast was notable for severe cerebellar atrophy. The patient subsequently underwent genetic testing which demonstrated a pathogenic and likely pathogenic variant in the Anoctamin 10 (ANO10) gene, which is seen in Autosomal Recessive Spinocerebellar Ataxia, Autosomal Recessive Type 10 (SCAR10). To our knowledge, this case represents the first reported instance of SCAR10 presenting with the sole neurologic exam finding of downbeat nystagmus without cerebellar ataxia. Additionally, the finding of severe cerebellar atrophy seen on MRI, without gait or limb ataxia on exam is an interesting clinicoradiological dissociation. This case suggests that nystagmus may represent an early disease marker, even in the absence of clinical ataxia in patients with SCAR10.

Humans↗
PubMed1978

Recessive male-determining genes.

The autosomal dominant gene polled (P) causes hornlessness in goats. Chromosomal females (XX) that are P/P homozygotes develop testes or ovotestes. Thus with respect to its testis-determining properties, P or a closely linked gene acts as an autosomal recessive. Polled intersex goats are H-Y+. This finding is consistent with the view that there may be a cluster of testis-determining H-Y genes on the Y chromosome, and that translocation of a subcritical portion of these genes may generate a recessive mode of sex determination.

Animals↗