Complicated decisionmaking in indications for auditory brainstem implant (ABI) in a patient with neurofibromatosis 2.

A case of an accidental finding of neurofibromatosis 2 in a practically asymptomatic patient is described. Various therapeutic modalities, including restoration of hearing after vestibular schwannoma surgery with an auditory brainstem implant (ABI), are considered.

Immunosuppression and feeding success of Ixodes ricinus nymphs on BALB/c mice.

The effect of repeated infestations of Ixodes ricinus (L.) nymphs on BALB/c mice was studied. Four successive infectations resulted in an increase of tick feeding success. Tick yield and mean engorged weight increased and the length of the feeding period was reduced significantly (P < 0.05-0.01). The increase of specific anti-tick antibodies was not significant (P > 0.05). The blastogenic response of spleen lymphocytes to T-cell mitogens (Con A and PHA-P) was unimpaired or slightly enhanced, whereas the response to B-cell activators (LPS and PWM) was suppressed, as was the total antibody generation in vitro. The numbers of mast cells in murine skin at the tick attachment sites slightly decreased during the third infestation. The suppression of B-cell competence and of antibody generation, together with decrease of skin mast cell numbers in tick attachment sits, are considered to be responsible for enhancement of tick feeding success.

Antigens and glycoproteins of larvae, nymphs and adults of the tick Ixodes ricinus.

Protein components of homogenates of unfed larvae and nymphs of Ixodes ricinus (L.), and of ovary, haemolymph, Malpighian tubules, rectal ampulla, fat body, integument, salivary glands and midgut of partially fed adult females were studied for their antigenicity and carbohydrate moieties using immunoblotting and lectin affinity blotting (LAB) techniques. Comparing the individual anti-larval, anti-nymphal and anti-adult immune sera for their capacity to recognize the specific and trans-stadially cross-reactive antigenic proteins, larval feeding induced the most effective humoral response. The majority of immunogens recognized by rabbit anti-tick immune sera are glycoproteins. Most of the glycosylated antigens were modified with N-type glycans; however, O-type glycans were also demonstrated in some antigens. The correlation of the type of glycosylation with antigenicity, and the sharing of common antigenic epitopes by various tissues, are discussed.

Humoral and cellular immune response of BALB/c mice to repeated infestations with Ixodes ricinus nymphs.

The capacity of female BALB/c mice to mount an immune response and effective resistance to repeated infestations with I. ricinus nymphs was studied. An anamnestic antibody response and transient in vitro responsiveness of spleen lymphocytes to tick antigens were demonstrated in repeatedly infested mice. On the other hand, the response to concanavalin A--a T-cell mitogen, was suppressed at the same time. In the presented experiment, BALB/c mice did not manifest tick resistance after three successive infestations (with a reinfestation period of 2 weeks). The possibility of an infestation-dependent modulation of immune response in BALB/c mice is discussed.

Age-dependent immune response of chickens to feeding by Argas persicus larvae.

Chickens of the dwarf Velsum breed acquired immunity to Argas persicus larvae during repeated infestations with 100 larval ticks in 2-week intervals, when primarily infested at the age of 10 weeks. This immunity was manifested by 74.6% and 75.9% rejection of larvae during secondary and tertiary infestations (P < 0.01), respectively, in relation to controls. The mean weight reductions observed were 16.5% and 12.2% in secondary and tertiary infestations, respectively (P < 0.05). Weak immunity also occurred after secondary and tertiary infestations in chickens infested first at the age of 6 and 8 weeks, but not in chickens aged 2 or 4 weeks at first infestation. No changes were observed in mean feeding periods of larvae engorged on chickens of all age groups (P > 0.05). A significant increase in the leucocyte counts in peripheral blood (P < 0.01 or P < 0.05), mostly of lymphocytes and heterophil granulocytes, followed each infestation in chickens of all age groups. Specific anti-tick circulating antibodies were detected by ELISA in the sera of 10-week-old chickens after primary infestations, in the 4-8-week chicken groups following secondary infestations when aged 6-10 weeks, and in the 2-week chicken group only after tertiary infestations, when the chickens reached the age of 6 weeks. A 53 kDa protein was recognized in the whole-body extract of larval ticks by immune serum during immunoblotting. This was probably the antigenic protein responsible for eliciting the circulating antibodies. The acquired immunity to ticks seen in chickens aged 6 weeks or more may be connected with maturation of the bursa of Fabricius and the development of complete immunocompetence, which is believed to occur in chickens at the age of 4-5 weeks.

Application of the relative summary climatic indices during work in heat for ergonomic purposes.

A new method was elaborated for the evaluation of work-heat load. Two indices of heat stress were introduced, the so-called 'climatic heat'--Hcl (a sum of convective, radiation, respiration and maximum evaporation heat), and the 'total heat'--Htot (a sum of metabolic and climatic heat). It is an adapted thermal balance equation in which the evaporation heat was replaced with maximum evaporation heat. This enabled the quantification of climatic load also in the normothermic region, where stored heat S=0. The applicability of these indices is given by the fact that so-called heat heart rate (HRh) is in good correlation with them. The above mentioned indices were used in the relative values of the 'quotient of heat stress' (Qdif,H) and of the 'grade of heat strain' (Gdif,H). These variables are basically a relation between real load and 'permissible' load to which a healthy adult male can be exposed for 8 h without an increase in his body temperature. In this paper, equations for calculation of those relative values according to heat stress indices are introduced. The relative indices show how many times is the real HRh larger (or smaller) than its permissible value (= 20 min(-1)). By joining the relative heat stress indices with the relative work load indices (Qdif,W and Gdif,W, respectively) the index of work-heat load is obtained. The permissible work heart rate (= 30 min(-1)), which corresponds with the energetic output in males (approximately 250 W). The work-heat strain grade (Gdif,WH) can be used for the quantification of load, for the determination of the rest allowance, of the necessary recovery time and for the determination of a suitable regime of work and rest in general. The permissible values of climatic elements under a given physical load, and the admissible duration of exposure under different climatic conditions and different muscle load intensities can be determined.