Hearing function in heterozygous carriers of a pathogenic GJB2 gene mutation.

The most frequent hereditary hearing loss is caused by mutations in the GJB2 gene coding for the gap junction beta 2 protein Connexin 26 (Cx26). In contrast to many studies performed in patients with bi-allelic mutations, audiometric studies on heterozygotes are sparse and often contradictory. To evaluate hearing function in heterozygous carriers of the GJB2 c.35delG mutation, audiometry over the extended frequency range and the recording of otoacoustic emissions (OAEs), i.e., transient-evoked OAEs (TEOAEs) and distortion product OAEs (DPOAEs), were performed in a group of parents and grandparents of deaf children homozygous for the GJB2 c.35delG mutation. The comparison of audiograms between control and heterozygous subjects was enabled using audiogram normalization for age and sex. Hearing loss, estimated with this procedure, was found to be significantly larger in GJB2 c.35delG heterozygous females in comparison with controls for the frequencies of 8-16 kHz; the deterioration of hearing in heterozygous men in comparison with controls was not statistically significant. A comparison of TEOAE responses and DPOAE levels between GJB2 c.35delG heterozygotes and controls did not reveal any significant differences. The results prove the importance of using audiometry over the extended frequency range and audiogram normalization for age and sex to detect minor hearing impairments, even in a relatively small group of subjects of different ages.

Nuclear spin effect on recombination of H3⁺ ions with electrons at 77 K.

Utilizing different ratios of para to ortho H2 in normal and para enriched hydrogen, we varied the population of para-H3⁺ in an H3⁺ dominated plasma at 77 K. Absorption spectroscopy was used to measure the densities of the two lowest rotational states of H3⁺. Monitoring plasma decays at different populations of para-H3⁺ allowed us to determine the rate coefficients for binary recombination of para-H3⁺ and ortho-H3⁺ ions: (p)α(bin)(77 K) = (1.9 ± 0.4) × 10⁻7 cm³ s⁻¹ and (o)α(bin)(77 K) = (0.2 ± 0.2) × 10⁻7 cm³ s⁻¹.

Psychosocial study of epilepsy in Africa.

As documented by many authors, the social position of epileptics in many small scale societies of Africa is marginal at best, and is often characterized by rejection, discrimination, even ostracism. Such negative and noxious attitudes toward persons suffering from epilepsy are rooted in traditional beliefs about causes and nature of convulsive disorders and these have parallels in European history. This article focuses on the psychosociocultural aspects and indigenous concepts of epilepsy, on popular attitudes towards, and social status of, sufferers from epilepsy in a Tanzanian tribal population. The authors present a comparative analysis of focus group discussions conducted with epileptics and with matched controls in two isolated communities. In one community (Mahenge) a clinic for epilepsy has been operating for over 36 years, with a public education component during the last four years, whereas in the other community (Ruaha) epileptics have only been sporadically treated in a small mission dispensary and people have had little opportunity to learn about the nature and modern treatment of convulsive disorders. The responses obtained in focus group discussions reflect the significant change in notions about the illness, in the attitude toward and in the social status of epileptics in Mahenge, while the people of Ruaha still regard epilepsy as a typical "African" affliction fraught with supernatural danger and not effectively treatable by modern medicine.

Auditory frequency and intensity discrimination in pigmented rats.

Auditory function was investigated in seven pigmented hooded rats (strain Long-Evans) with the aid of an operant conditioning procedure. Frequency difference limen was measured at frequencies from 0.5 to 64 kHz at 50 dB sensation level (SL). Weber ratios (frequency difference limen/frequency) in this range varied between 3.7 and 7.3%. The decline in the intensity of the stimulus from 50 to 10 dB SL was accompanied by a slight increase in the frequency difference limen. The frequency difference limen values were similar for frequency shifts upwards or downwards. Intensity discrimination was measured at 50 dB SL at frequencies of 2, 8 and 32 kHz. Intensity difference limen was frequency independent and amounted to 2.9 +/- 0.5 dB in conditions of upward intensity shift. The values of intensity difference limen measured in conditions of downward intensity shift were significantly larger and amounted to 6.5 +/- 1.6 dB. The characteristics of hearing function found in these experiments correspond with those described by other authors in albino rats and indicate that albinism in the rat has no significant influence on auditory frequency and intensity discrimination.

Class IgG, IgM and IgA antibodies against Staphylococcus aureus antigens in human serum and saliva.

Using the ELISA method antibodies against the sonicate, teichoic acid (TA) and exoproducts of Staphylococcus aureus were determined in sera and saliva of healthy individuals. Main serum antibodies against all the antigens used were shown to be class IgG antibodies. However, antigens of the sonicate stimulated significantly even the systemic IgA response. In the saliva class IgA antibodies predominated, but IgG antibody levels against TA and exoproducts approached the level of IgA antibodies. Levels of IgM antibodies against all antigens tested were low in both the serum and saliva which corresponds with the anamnestic type of response. On the basis of these results one may assume that not only IgG, but also IgA antibodies are important in the systemic immunity against staphylococcal infection and in the immunity of mucous membranes; besides IgA, even class IgG antibodies play an important role.

The number of plaque-forming cells and its "normal range".

The number of antibody-forming cells is commonly assessed by the plaque technique. In this paper, two questions are discussed, connected with presenting the number of plaque-forming cells found in experiments: (i) the form of probability distribution of the number of plaque-forming cells (PFC), and (ii) determination and use of the so-called "normal range" of the number of PFC. Gottlieb's finding (1974) that the lognormal distribution is a good approximation to the distribution of the number of PFC is supported, and it is suggested that the upper one-sided tolerance limit be used as the limit of normal range of the number of PFC. A numerical study based on 1,450,000 pseudo-random experiments shows that it is important to make a correct assumption about the form of the distribution before a statistical method is used.

A new mathematical model of proliferation control during immune response.

A considerable proliferation of participating cells is a characteristic feature of the immune response. This proliferation may be controlled by Interleukin 2. Assumptions on the course of the immune response under such a control are formulated, and a new mathematical model of the immune response involving regulation of the proliferation of appropriate cells is constructed.

The X----Y----Z scheme after 23 years.

Mathematical modelling of the course of the immune response is undoubtedly one of the most progressive and most promising areas of modern immunology. Mathematical models (along with computer programs) can be taken as "the only means of thoroughly testing and examining a large and intricate theory" (Partridge et al. 1984). The first phase of construction of mathematical models is the formulation of assumptions based on the knowledge of the facts to be modelled (manifested usually in a scheme of the presumed course of the modelled process). The first mathematical models of immune response were based on the hypothesis of a two-stage differentiation of cells participating in the humoral response, published in Prague 23 years ago (Sercarz and Coons 1962; Sterzl 1962) and illustrated by the X----Y----Z scheme. Many contemporary mathematical models still stem from this scheme which undoubtedly fits the fundamental data concerning the immune system.

Immunogenetic studies in semi-inbred pigs.

Seventy-six siblings from 11 semi-inbred families of Landrace pigs (inbreeding coefficient 0.70-0.82) were used for transplantation of skin and renal allografts. The animals were selected with regard to the major histocompatibility complex SLA, alloantigenic systems SLB, SLC and blood groups. Using the test of the difference in mean level between two groups of observations, the influence of compatibility in the E blood group system on the survival of transplants was proved. The observed difference suggests that the E blood group complex or a linked locus behaves as a minor histocompatibility system. The induction of tolerance in piglets treated and non-treated with allogeneic sera from long-term liver recipients was also investigated. Large doses of sera did not exert any effect on skin graft survival.

An estimate of the number of cells arising by division in mouse cerebral hemispheres from age one to 12 months: an autoradiographic study of DNA synthesis.

Male CBA strain mice aged 1, 2, 4, 6, 8 and 12 months were injected with 5 muCi of 6-H3-thymidine per gm body weight and killed two hours after the injection. Incorporation of the isotope, as a measure of DNA synthesis and cell division, was studied in the cerebral cortex and corpus callosum by light-microscope autoradiography. DNA synthesis was found in a small number of nuclei of non-neuronal cells, both of ecto- and mesodermal origin. The percentage of labeled cells (Labeling Index, or LI) decreased in both regions exponentially with age. On the base of measured LI values, the total number of cells arising from age one to 12 months was calculated. As the reference value the number of cells in one month-old animals was taken. The calculated cell increment in the ectodermal population in the cortex amounted to 19.7-20.6% (average 20.2%) and to 196.0-425.0% (average 247.0%) in the corpus callosum (pairs of figures correspond to values calcualted from LI values measured in sagittal and frontal sections). When all labeled cells (LC) were taken into consideration (of both ecto- and mesodermal origin) the corresponding cell increment ranged from 25.0-30.5% (average 26.8%) in the cortex and from 205.0-454.8% (average 263.0%) in the corpus callosum. The number of all newly arising cells in the whole hemisphere (including both cerebral cortex and corpus calosum) calculated from mean LI values of all LC in sagittal and frontal sections amounted to 52.0%. It is suggested that the observed DNA synthesis and cell division, particularly in the corpus callosum and mesodermal cell groups of both regions studied, correspond mainly to renewal of cell populations. In the cerebral cortex accumulation of some newly arising cells in situ cannot be excluded.