Analysis of saccadic short-term plasticity in three dimensions

The capacity for short-term adaptation is a well-established property of the horizontal (H) and vertical (V) components of saccades. It allows these directional components, which clearly serve the goal of foveation, to maintain their precision even under changing circumstances. Torsional (T) saccade components, on the other hand, which deal with the orientation of the target on the fovea, have hardly been investigated in adaptation experiments. They appear to be severely restricted by Listing's law during fixations and saccades. The main purpose of Listing's law is far from obvious but could be visual or oculomotor. Better knowledge of the adaptive capacity of the saccadic system in the torsional direction could throw new light on the functional significance of this interesting neural strategy. To study short-term plasticity in the torsional components of saccades, binocular 3D-eye positions were measured, using magnetic search foils. Five normal human subjects were instructed to make uni-directional refixation saccades, while they viewed a large visual scene. To induce a change in the torsional component, the complete stimulus was rapidly rotated during these saccades. We thoroughly investigated the torsional responses of the saccadic system, to see if any short-term adaptive response in torsional direction was induced, in which case the notion of a visual purpose for Listing's law would be strengthened. In none of our experiments, however, did we find any clear adaptive response in torsional direction. To further investigate the reliability of this result and to ascertain that our experimental conditions allowed classical gain adaptation, we also did experiments designed to achieve a combination of torsional adaptation and classic gain shortening in one of the directional components. While gain adaptation was very obvious, none of the experiments provided evidence for a short-term effect in torsion. We conclude that our experiments do not support a purely visual basis for Listing's law.     

Translocation of BCR to chromosome 9: A new cytogenetic variant detected by FISH in two Ph-negative,BCR-positive patients with chronic myeloid leukemia

Leukemic cells from two patients with Philadelphia-negative chronic myeloid leukemia (CML) were investigated: I) Cytogenetics showed a normal 46.XY karyotype in both cases, 2) molecular studies revealed rearrangement of the M-BCR region and formation of BCR-ABL fusion mRNA with b2a2 (patient I) or b3a2 (patient 2) configuration, and 3) fluorescence in situ hybridization (FISH) demonstrated relocation of the 5′ BCR sequences from one chromosome 22 to one chromosome 9. The ABL probe hybridized to both chromosomes 9 at band q34, while two other probes which map centromeric and telomeric of BCR on 22q 11 hybridized solely with chromosome 22. For the first time, a BCR-ABL rearrangement is shown to take place on 9q34 instead of in the usual location on 22q 11. A rearrangement in the latter site is found in all Ph-positive CML and in almost all investigated CML with variant Ph or Ph-negative, BCR-positive cases. The few aberrant chromosomal localizations of BCR-ABL recombinant genes found previously were apparently the result of complex and successive changes. Furthermore in patient 2, both chromosomes 9 showed positive FISH signals with both ABL and BCR probes. Restriction fragment length polymorphism (RFLP) analysis indicated that mitotic recombination had occurred on the long arm of chromosome 9 and that the rearranged chromosome 9 was of paternal origin. The leukemic cells of this patient showed a duplication of the BCR-ABL gene, analogous to duplication of the Ph chromosome in classic CML. In addition they had lost the maternal alleles of the 9q34 chromosomal region. The lymphocytes of patient 2 carried the maternal chromosome 9 alleles and were Ph-negative as evidenced by RFLP and FISH analyses, respectively. © 1993 Wiley-Liss, Inc.     

Abstracts of the contributed papers

Abstracts of the contributed papers     

PRKCG mutation (SCA-14) causing a Ramsay Hunt phenotype.

Progressive myoclonic ataxia, also referred to as Ramsay Hunt syndrome, is characterized by a combination of myoclonus and cerebellar ataxia, infrequently accompanied by tonic-clonic seizures. Its differential diagnosis overlaps with progressive myoclonic epilepsy, a syndrome with myoclonus, tonic-clonic seizures, progressive ataxia and dementia. In patients with progressive myoclonic epilepsy, specific diseases can frequently be recognized, but the diagnostic yield in progressive myoclonic ataxia is much lower. We describe a patient who presented with multifocal myoclonus in his thirties and who later developed cerebellar ataxia and focal dystonia. His father was similarly affected. Genetic studies revealed a mutation in the protein kinase C gamma (PRKCG) gene, known to cause spinocerebellar ataxia type 14 (SCA-14). This case illustrates that both myoclonus and dystonia are part of the clinical spectrum in SCA-14 and that myoclonus can even be the presenting symptom. We suggest that SCA-14 should be considered in the differential diagnosis of progressive myoclonic ataxia.     

Bladder filling by autologous urine production during cystometry: a urodynamic pitfall!

AIMS: The rate of autologous urine production should not have a major disturbing influence on cystometric urodynamic parameters such as first filling sensation, normal desire to void, strong desire to void, and cystometric bladder capacity. Instructions to patients and drinking behavior can have considerable impact, especially if filling cystometry is preceded by free uroflowmetry. We studied the influence of autologous urine production during filling cystometry on total bladder volume. METHODS: Urodynamic investigations performed between September of 2000 and February of 2001 were analyzed. Only those urodynamic investigations for which total bladder capacity could be calculated were taken into account (i.e., catheterization before and after cystometry and no urine loss during the investigations). RESULTS: After screening, 186 investigations were used for further analysis. Mean filled volume (external infusion plus autologous urine production) was 346 +/- 152 mL, but mean real bladder capacity (i.e., voided volume + residual urine) was 391 +/- 170 mL. In all patients, 14% extra urine was produced due to autologous urine production (mean filling rate, 6.1 mL/min). In 42% of the investigations, the real bladder capacity was more than 110% of the infused volume. In 18% of the patients, the contribution of natural bladder filling was more than 25% of the infused volume. CONCLUSIONS: Natural bladder filling plays a substantial role during filling cystometry and has a disturbing influence on calculated urodynamic parameters. Attention should be paid to patient instructions before the urodynamic investigation. The combination of free uroflowmetry followed by filling cystometry should be avoided. This avoidance is especially important if interventional studies are performed. Careful interpretation of studies depending on bladder capacity parameters is mandatory, and such parameters should be corrected for autologous bladder filling.     

Propriospinal myoclonus after treatment with ciprofloxacin.

The clinical and electrophysiological features of a truncal myoclonus in a 55-year-old man are described. The electromyographic characteristics point toward propriospinal myoclonus. It is suggested that a myoclonic generator was released after use of ciprofloxacin, by antagonising the gamma-aminobutyric acid metabolism.     

Natural history of parathyroid function and calcium metabolism after kidney transplantation: a single-centre study.

BACKGROUND: The natural history of parathyroid function after successful renal transplantation (RT) and the factors predisposing to persistent hyperparathyroidism (HPT) are not well established. A better knowledge of these data may be helpful in the development of algorithms for optimal surveillance and treatment of HPT after successful RT. Our aim was to evaluate the post-transplant natural history of parathyroid function and calcium metabolism in patients with a functional renal graft and to identify risk factors for persistent HPT. METHODS: Charts of 1165 allograft kidney recipients transplanted between 1989 and 2000 were reviewed. Patients with an intact parathyroid hormone (iPTH) level available at the time of transplantation were identified. The charts of the latter patients were checked for a variety of demographic and clinical data, and all determinations of the iPTH concentration available since transplantation were recorded. Serum levels of calcium, phosphorus, alkaline phosphatases and creatinine, concurrently determined, were also registered. RESULTS: After an initial fall, iPTH levels showed a slow but steady decline towards the upper normal limit. The prevalence of persistent HPT, defined as an iPTH level > or =2.5 times the upper normal limit or the need for parathyroidectomy following transplantation, remained stable at approximately 17% up to 4 years after transplantation. Patients with persistent HPT had significantly elevated serum levels of iPTH, calcium and phosphorus at the time of RT, and had spent a longer time on dialysis. Post-transplant iPTH levels correlated significantly with transplant kidney function. CONCLUSION: Kidney transplant recipients with a high iPTH and calcium x phosphate product at the time of transplantation are at risk for persistent HPT especially when renal function is suboptimal. Therapy for persistent HPT, if considered, should be initiated 3 months post-transplantation since further spontaneous improvement of parathyroid function thereafter is limited.     

Functional signatures of protective antiviral T-cell immunity in human virus infections

Summary: The most common human viruses have different abilities to establish persistent chronic infection. Virus‐specific T‐cell responses are critical in the control of virus replication and in the prevention of disease in chronic infection. A large number of phenotypic markers and a series of functions have been used to characterize virus‐specific CD4⁺ and CD8⁺ T‐cell responses, and these studies have shown great phenotypic and functional heterogeneity of the T‐cell responses against different viruses. The heterogeneity of the T‐cell response has been proposed to be specific to each virus. However, over the past 2 years, several studies have provided evidence that the phenotypic and functional heterogeneity of CD4⁺ and CD8⁺ T‐cell responses is predominantly regulated by the levels of antigen load. The levels of antigen load modulate the phenotypic and functional patterns of the T‐cell response within the same virus infection. Furthermore, the functional characterization of virus‐specific CD4⁺ and CD8⁺ T‐cell responses has identified signatures of protective antiviral immunity. Polyfunctional, i.e. interleukin‐2 and interferon‐γ (IFN‐γ) secretion and proliferation, and not monofunctional, i.e. IFN‐γ secretion, CD4⁺ and CD8⁺ T‐cell responses represent correlates of protective antiviral immunity in chronic virus infections.     

Acanthoma supratrochantericum.

We report the cases of five patients with lesions of benign reactive hyperplasia of the skin in the hip joint region. In view of the distinct clinical features, and in analogy with previously reported cases of acanthoma fissuratum, we termed this condition acanthoma supratrochantericum.