Visually evoked slow eye movements, visual-vestibular interaction, and infratentorial lesions

The maximum velocity gain of smooth pursuit and optokinetic, vestibular, and optovestibular slow phases was examined in 15 patients with pontine, 10 with medullary, 10 with cerebellar, and 5 with combined cerebello-brain stem disorders. Marked dissociations were observed between smooth pursuit and optokinetic slow phases, especially in medullary disease. A cerebellar deficit enhanced slow phase velocity gain during rotation in darkness, whereas the corresponding gain during rotation in light was normal.

A reduction of vestibulo-visual integration during transdermally administered scopolamine and dimenhydrinate. A presentation of gain control theory in motion sickness

The effect of transdermally administered scopolamine (TTS scopolamine) (release rate 5 micrograms/h) and dimenhydrinate (100 mg) was examined on optovestibular nystagmus in 16 volunteers in a randomized double-blind trial. A statistically significant decrease in the optokinetic part of nystagmus was observed during all treatments. Most profound reduction was found during treatment with two TTS scopolamine. The vestibular part was reduced by treatment with two TTS scopolamine, only. The results indicate that scopolamine and dimenhydrinate exert their effect in motion sickness by reducing the vestibular and visual influx and by partly inhibiting the integrative functioning of the vestibular nuclei. In their action, the motion sickness drugs seem to assist the cerebellum by diminishing impulses from various orientation reflexes in order to preserve the functional capacity of the central nervous system. Different symptoms in motion sickness seem to arise when the vestibular gain operates beyond the normal range of the cerebellar control mechanisms.

Intra-individual variation in oculomotor performance in man

Peak velocity of saccade, maximum velocity of smooth pursuit, and peak velocity of slow phase of vestibular and optovestibular nystagmus were measured three times daily on three separate days in 6 healthy subjects in order to estimate the intra-individual variation of the results of oculomotor tests. Analysis of variance revealed that the oculomotor performance of the individual subjects varied systematically, depending on whether the tests were performed in the morning, at noon, or late in the afternoon. In particular, the velocity of saccade displayed lowest values in the afternoon. The present results indicate that oculomotor performance may depend on the individual biological rhythm of fatigue; however, it is also possible that eye motor behaviour is coupled to an independent rhythm of motor activity. Circadian rhythmicity of oculomotor performance should be considered in follow-up studies and in examination of patients with reduced vigilance.

Classification of Mycobacterium simiae by means of comparative reciprocal intradermal sensitin testing on guinea-pigs and deoxyribonucleic acid hybridization

This study is a contribution to the elucidation of the taxonomic relationships among Mycobacterium simiae serovars 1 and 2, other photochromogenic, mycobacterial species and the non-photochromogenic species M. avium and M. intracellulare. DNA-DNA homology percentages and comparative reciprocal intradermal sensitin reactions in guinea-pigs have confirmed that M. habana is a subjective synonym of M. simiae serovar 1 and that M. asiaticum is a separate species. The two strains of M. simiae serovar 2 studied were distinct from each other and both were distinct from M. simiae serovar 1. M. simiae was so different from M. avium and even from M. intracellulare serovars 12, 14, 16 and 19, that there is no basis for including M. simiae in the so-called M. avium-intracellulare complex. Neither did M. simiae bear any close relation to the photochromogenic species M. kansasii and M. marinum. A fairly close negative correlation was observed between the DNA-DNA homology percentages and the specificity differences of the sensitins from the same pairs of strains. This is per se a proof of the veracity of the two taxonomic methods used in the study.

Mycobacterial sensitins: where are we now?

A limited review of the results of using comparative reciprocal intradermal mycobacterial sensitin (CRIS) testing with guinea pigs for the classification and identification of mycobacteria is presented. The technical procedures and the materials used in CRIS testing are referred to only briefly. Strains of mycobacteria that grow well on a synthetic nonimmunogenic medium can be identified or classified at the species level with this method. At present some 50 species of mycobacteria can be identified by CRIS testing. With this method alone, delineation between the genera Mycobacterium and Nocardia (or between subgenera of Mycobacterium proposed earlier) and differentiation between individual strains of Mycobacterium tuberculosis, Mycobacterium bovis, and Mycobacterium africanum are not possible. In a blind study that utilized CRIS testing, a total of 10 strains of Mycobacterium avium complex serovars 1, 2, 4, and 6 and one strain of serovar 9 were identified as M. avium; a total of five strains of serovars 14, 16, 17, and 20 and one strain of serovar 12 were identified as Mycobacterium intracellulare; a total of seven strains of serovars 41, 42, and 43 and two other strains of serovar 9 were identified as Mycobacterium scrofulaceum; and two other strains of serovar 9 appeared to be distinct from M. avium and from the other two species just mentioned (author's unpublished data). CRIS tests cannot be used at present for the identification of mycobacteria that cannot be cultivated.

The antigens of Mycobacterium bovis, strain BCG, studied by crossed immunoelectrophoresis: a reference system

A reference system for the soluble antigens of Mycobacterium bovis, strain BCG is described. The system is based on crossed immunoelectrophoresis with intermediate gel. A commercially available immunoglobulin preparation made from rabbit anti-BCG hyperimmune serum was used as reference antibodies, while a concentrated BCG culture filtrate was used as reference antigen. The pattern obtained was highly reproducible, and most of the components were stable when the fiftyfold-concentrated culture filtrate was stored at -20 degrees C. About thirty different antigenic components were selected as reference antigens and numbered. The majority of the reference antigens were present in extracts prepared from BCG by ultrasonication or bacterial press extraction. Use of the system for studies of antigenic relationship between mycobacteria, identification and quantification of antigens, and characterization of antimycobacterial antibodies are illustrated by examples. The antigens of two preparations of tuberculin purified protein derivative (PPD) were identified. The antigen designated BCG60 was found to be a najor constituent of tuberculin PPD. Evidence is presented that this antigen is cell wall associated.

Effect of immunologic donor pretreatment on survival of perfused canine renal allografts

We evaluated the effect of immunologic donor pretreatment followed by perfusion preservation on canine renal allograft survival. Donor-recipient pairs were selected on the basis of dog erythrocyte identity, a negative white blood-cell crossmatch, equivalent dog leukocyte matching, and significant mixed lymphocyte culture stimulation. Four hours before nephrectomy, all donors were pretreated with either normal saline or cyclophosphamide and methylprednisolone. After donor nephrectomy, all grafts were preserved by pulsatile perfusion for 24 hr. Transplantation into the matched recipient was performed with simultaneous bilateral nephrectomy. No significant difference was found in the postoperative serum creatinine levels or median allograft survival between the two groups. This controlled study showed no beneficial effect of donor pretreatment on survival of perfused canine renal allografts.

Multiple-artery renal transplantation: emphasis on extracorporeal methods of donor arterial reconstruction

The operative techniques to transplant kidneys with multiple renal arteries and our recent experience with them are reviewed. The preferred methods are anastomosis with a Carrel aortic patch and extracorporeal arterial repair before transplantation. These are simple and effective methods that avoid subjecting the kidney to prolonged ischemia. Revascularization of all renal arteries is important to obviate ischemic allograft complications.

Impaired renal allograft function: a comparative study with angiography and histopathology

We reviewed 47 renal transplant recipients who had undergone angiography and transplant biopsy to evaluate impaired allograft function. Angiographic criteria for rejection were seen in all allografts with hyperacute rejection, accelerated rejection and chronic rejection, and in 13 of 17 allografts with acute cellular rejection. Angiography was normal in allografts with vasomotor nephropathy or transplant glomerulopathy. Angiography is an accurate method for the diagnosis of most causes of post-transplant dysfunction.

Protective effect of propranolol in the treatment of ischemically damaged canine kidneys prior to transplantation

Warm ischemia is a potential problem during the harvesting of cadaveric kidneys for transplantation purposes. This ischemia can cause impaired renal function following transplantation. The purpose of our study was to determine whether the beta-adrenergic blocking agent propranolol was effective in improving renal function after ischemia. Dog kidneys were subjected to 30 minutes of warm ischemia followed by hypothermic pulsatile preservation for 24 hours. The kidneys then were autotransplanted with immediate contralateral nephrectomy. In this model only 50% of the untreated control group survived. Three different protocols using propranolol were tested. Administration of propranolol to dogs before the ischemic period, or installation of propranolol into the renal artery at the start of the ischemia, or addition of propranolol to the preservation perfusate lessened the severity of acute tubular necrosis and resulted in 100% long-term survival. Although the mechanism was not investigated, it has been suggested that propranolol is acting through its blockade of beta-mediated renin release and/or through its so-called membrane-stabilizing effect.

The effect of two different renal preservation methods on canine renal allograft survival

Preservation of human cadaver kidneys for transplantation has been achieved primarily by two methods, hypothermic pulsatile perfusion with cryoprecipitated plasma and cold storage with an electrolyte solution. It has been suggested that pulsatile perfusion results in an increased antigenicity of the transplanted kidney. To investigate the possibility that pulsatile perfusion causes changes which may accelerate allograft rejection, machine preservation was compared with simple cold storage. The kidneys were preserved by either one of the two methods for 6 or 24 hours followed by allotransplantation in nephrectomised dogs. No immunosuppressive drugs were given. Kidneys which were allografted without undergoing any preservation (0 hrs) had a mean survival time of 10.4 +/- 1.7 days (n =5). Kidneys preserved by machine perfusion for 6 and 24 hours survival for 9.6 +/- 1.4 (n = 5) and 10.9 +/- 1.3 (n =9) days respectively. The mean survival time for simple cold storage for 6 and 24 hours was 9.3 +/- 1.3 (n =7) and 12.0 +/- 1.9 (n =6) days. Our findings suggest that in kidneys exposed to minimal warm ischaemia there is no significant difference between the two methods of preservation on renal allograft survival for the time intervals tested.