Generation of T cells with lytic specificity for atypical antigens. III. Priming F1 animals with antigen-bearing cells also having reactivity for host alloantigens allows for potent lytic T cell responses.

Here, we explore the conditions required for generating two different highly potent F1 antiparental killer cell populations to unusual antigens in rats. The first, L/DA anti-DA, has lytic specificity for two antigen systems: MTA, a mitochondrial antigen expressed on DA and DA Lewis (L) target cells restricted by RT1A class I molecules; and H, an antigen that maps to the class I-like RT1C region and is present only on parental target cells from donors homozygous at the major histocompatibility complex. The second killer population is generated in the reciprocal DA/L anti-DA combination and has lytic specificity only for the H antigen system. We show that the killer cells are T cells, and that generation of these F1 cytotoxic T lymphocytes (CTL) requires an in vivo priming step in which it is essential that the inoculated parental cells bear the relevant target antigens and possess alloreactivity for F1 host antigens. The requirement for alloreactivity and antigen on the same priming cell population suggests that these potent lytic responses depend on a situation akin to a hapten-carrier effect that bypasses otherwise ineffective helper responses by the host to these unusual antigens. Restimulation of F1 lymphocytes in culture is also necessary, requiring the presence of antigen on irradiated lymphoblast stimulator cells, but alloreactivity to responder cell antigens is not necessary; normal, nonactivated lymph node cells are completely ineffective as stimulators. For effective lysis, the target cells need not possess the potential for alloreactivity to responder F1 CTL. We also demonstrate in a preliminary way additional antigen systems defined by killer populations raised with other F1 antiparental strain combinations.

The generation of killer cells to trinitrophenyl-modified allogeneic targets by lymphocyte populations negatively selected to strong alloantigens.

Negatively selected mouse and rat lymphocyte populations, specifically deprived of alloreactivity to a particular major histocompatibility complex (MHC) haplotype, are nevertheless fully capable of responding to trinitrophenyl (TNP)-modified allogeneic stimulator cells and developing cytotoxic T-lymphocyte activity to TNP-altered allogeneic target cells. As for syngeneic systems, lytic expression of those responder killer cells also requires MHC identity between the target and stimulator cell populations. Such a finding argues strongly against two variations of the dual recognition hypothesis: like-like interactions and adaptive differentiation. Instead, these data favor either the altered self model or a third variation of the dual receptor model, where one of the relevent receptors is specific for the modifying antigen and the second is a low affinity receptor unable to be triggered in the absence of a modifying antigen.

Generation of T cells with lytic specificity for atypical antigens. II. A novel antigen system in the rat dependent on homozygous expression of major histocompatibility complex genes of the class I-like RT1C region.

Lymphocytes from parental strain DA rats can induce potent killer cell responses to atypical antigen systems in F1 Lewis (L)/DA and DA/L recipients. Here, we describe an antigen system, H, present on homozygous parental target cells, but not on F1 cells. This antigen system is unusual in several respects: it does not involve class I RT1A gene products usually used by killer cell responses in the rat, it maps to the major histocompatibility complex (MHC) class I-like RT1C region, and it requires homozygous expression of RT1Cav1 alleles. This may be another example, this time involving the RT1C region, of an MHC gene product antigenically altered by an MHC-linked trans-activating modifier gene.

Cyclosporine-induced autoimmunity. Conditions for expressing disease, requirement for intact thymus, and potency estimates of autoimmune lymphocytes in drug-treated rats.

These studies explore the phenomenon of cyclosporine-induced autoimmunity in irradiated Lewis rats. We show that (a) the presence of a thymus is required, and autoimmune precursors develop in and exit from this organ to the peripheral lymphocyte pool within a 2-wk period after the initiation of cyclosporine treatment; (b) adoptive transfers of drug-induced autoimmunity to irradiated secondary recipients can be accomplished with relatively few cells of the Th subset, and these transfers of autoimmunity can be blocked by cotransfer of normal lymphoid cells; and (c) potency estimates, using popliteal lymph node assays in syngeneic and F1 recipients indicate similar levels of auto- and alloreactivity by cells from drug-induced autoimmune donors. These various findings indicate that this particular animal model may be useful for studies of the onset and control of autoimmunity, and they raise the possibility that the lack of autoimmunity in normal animals and its induction with cyclosporine may involve similar cellular mechanism as have been found to be operative in GVH reactions and specifically induced immunologic resistance to GVHD.

Generation of T cells with lytic specificity for atypical antigens. I. A mitochondrial antigen in the rat.

F1 rats primed with normal parental strain lymphocyte populations and restimulated in culture with parental lymphoblasts generate potent cytotoxic T cell responses to unusual antigen systems. Here we describe in the Lewis (L)/DA anti-DA combination an antigen system most likely of mitochondrial origin with the following properties: it is transmitted maternally from DA strain females, inherited in an extra-chromosomal manner, restricted by class I RT1Aa major histocompatibility complex gene products, extinguished on target cells treated with chloramphenicol, and its pattern of expression in different rat strains correlates with restriction fragment-length polymorphisms of mitochondrial DNA. Sequence analysis of the rat ND1 gene indicates that the maternally transferred factor in the rat is not a homologue of the maternally transmitted factor responsible for the mitochondrial antigen in mice. In keeping with its inheritance from DA females, this antigen is present on target cells from (DA female x L male)F1 donors and all other F1 combinations derived from DA female parents, but absent from target cells from some F1 combinations (L/DA and Wistar-Furth [WF]/DA) derived from DA strain males. The presence of this antigen in other F1 combinations (Brown Norway [BN]/DA, August 2880 [AUG]/DA, and PVG/DA) indicates that this mitochondrial antigen system is shared by the DA, BN, and PVG strains, but not by the L and WF strains.

Non-canonical Wnt signalling regulates scarring in biliary disease via the planar cell polarity receptors.

The number of patients diagnosed with chronic bile duct disease is increasing and in most cases these diseases result in chronic ductular scarring, necessitating liver transplantation. The formation of ductular scaring affects liver function; however, scar-generating portal fibroblasts also provide important instructive signals to promote the proliferation and differentiation of biliary epithelial cells. Therefore, understanding whether we can reduce scar formation while maintaining a pro-regenerative microenvironment will be essential in developing treatments for biliary disease. Here, we describe how regenerating biliary epithelial cells express Wnt-Planar Cell Polarity signalling components following bile duct injury and promote the formation of ductular scars by upregulating pro-fibrogenic cytokines and positively regulating collagen-deposition. Inhibiting the production of Wnt-ligands reduces the amount of scar formed around the bile duct, without reducing the development of the pro-regenerative microenvironment required for ductular regeneration, demonstrating that scarring and regeneration can be uncoupled in adult biliary disease and regeneration.

Cognitive interaction after staged callosal section: evidence for transfer of semantic activation.

Sensory and cognitive functions were assessed in a right-handed male before and after partial and complete callosal commissurotomy. After the initial posterior section was made, there was no evidence of interhemispheric sensory transfer, although the left hemisphere did have access to stimulus-related semantic and episodic information from the right hemisphere. After the callosum was completely sectioned, this exchange was no longer observed.

Block design performance following callosal sectioning. Observations on functional recovery.

A patient with complete surgical section of the corpus callosum was tested on a constructional task 17 months post-operatively. The left and right hands were separately tested under conditions of free visual exposure and lateralized visual field exposure. The results suggest that the typically observed improved performance of the right hand with increasing postoperative time is attributable to the acquisition of homolateral control over the right hand by the right hemisphere. The implications for left-right brain organization and the syndrome of constructional apraxia are considered.

Division of the corpus callosum for uncontrollable epilepsy.

Cerebral commissurotomy, the "split-brain" procedure, has been employed for the control of intractable seizures, in conjunction with moderate doses of anticonvulsant drugs. The results have been encouraging in several small series. The use of microsurgical techniques and the restriction of surgery to one commissure, the corpus callosum, has reduced morbidity without apparent change in result. The eight patients in our first series who underwent the prescribed division of several forebrain commissures are compared to the four patients in our second series who underwent division of the corpus callosum alone. The technique of callosotomy is described.

Cerebral commissurotomy for control of intractable seizures.

Cerebral commissurotomy or the "split-brain" procedure may be a valuable adjunct to anticonvulsants for the control of seizures in people whose epilepsy cannot be relieved by anticonvulsants alone, and who are not candidate for the standard methods of surgery. Corpus callosotomy, a revised form of the usual division of many commissures, is a safer operation and appears to be equally effective. The complex clinical aspects of cure and treatment are emphasized.

Disconnection of the cerebral hemispheres. An alternative to hemispherectomy for the control of intractable seizures.

A boy with intractable siezures that had progressed to about 30 a day underwent complete disconnection of the cerebral hemispheres in January 1972. Using microsurgical technique, we followed the path described by Bogen and Vogel requiring division of the corpus callosum from rostrum to splenium, the anterior commisure, one fornix, and hippocampal commissure. Postoperative recovery was complicated by aseptic meningitis, which was treated with dexamethasone and, later by hydrocephalus, which was reduced by ventriculoperitoneal shunt. The patient improved rapidly and remains well. We believe that disconnection is a preferred alternative to hemispherectomy for control of intractable seizures arising from early damage to one cerebral hemisphere.

Language, praxis, and the right hemisphere: clues to some mechanisms of consciousness.

The linguistic capacity of each separate cerebral hemisphere was examined in a 15-year-old, callosally sectioned, normally right-handed male. The results demonstrated that while the right hemisphere was not capable of expressive speech, it could comprehend nouns and verbs, and also possessed the motor engrams necessary to carry out verbal and pictorial commands. In addition, the mute hemisphere was found to be capable of spelling the names of visually presented items by arranging letters as well as by writing with the left hand. Finally, the manner in which the left hemisphere dealt with the overt bodily response to commands presented to the right hemisphere suggested clues to what we feel are mechanisms by which a personal sense of conscious reality is created in the normal brain.

"Central" commissurotomy for intractable generalized epilepsy: series two.

A second consecutive series of 12 patients underwent microsurgical "central" commissurotomy (division of the entire corpus callosum and hippocampal commissure) for the relief of previously intractable generalized seizures. This modified operation was found to be safer than the multiple commissurotomies performed in the first series of eight patients and was equally effective. Central commissurotomy was modified further by being performed in two stages, which reduced the length and severity of the "acute disconnection syndrome," a common cause of morbidity in the early postoperative phase. Best results were obtained in patients who were not severely retarded, had signs of unilateral cerebral damage, and included akinetic spells as a prominent form of their generalized seizures. EEG showed that bilateral symmetric discharge became either unilateral or asymmetric after surgery, which emphasized the important role played by the corpus callosum in conducting seizure discharges from one hemisphere to the other.

Psychologic and neurologic consequences of partial and complete cerebral commissurotomy.

Preliminary psychologic testing was carried out on four patients who had undergone surgical sectioning of a portion or all of the corpus callosum and anterior commissure as a treatment for uncontrollable seizures. Results confirm earlier findings indicating the importance of the forebrain commissures in the interhemispheric exchange of a variety of sensory and motor information, and demonstrate that particular portions of the commissural system are responsible for transferring the information of specific sensory modalities. The patients also showed surprising abilities in performing complex tasks assumed to require integration of information from both hemispheres.

Cortical mechanisms involved in praxis: observations following partial and complete section of the corpus callosum in man.

In patients who have undergone complete section of the corpus callosum for intractable epilepsy, lateralized presentation of visual nonverbal stimulation showed that the coordination of motor acts by either hand is controlled exclusively by the contralateral hemisphere. When two patients had serial operations consisting of an initial division of the splenium and posterior 3 cm, followed by complete callosal division, an opportunity arose to test the explicit cortical pathways involved in ipsilateral control. Between operations, these patients could not coordinate movements of the hand ipsilateral to the hemisphere receiving the command. This suggested that for visual nonverbal stimulation, the posterior 3 cm of corpus callosum is necessary for control of the ipsilateral hand; the rostral callosum cannot transfer sensorimotor commands. Also, contrary to current views, each hemisphere can carry out sequentially dependent motor activity.

Dynamic light scattering investigations of RecA self-assembly and interactions with single strand DNA.

Dynamic light scattering (DLS) measurements were performed on self-assembled solutions of RecA as a function of assembly time under strand exchange ionic strength conditions (10 mM MgCl2, 65 mM NaCl, 10 mM Tris-HCl, pH = 7.5, 1 mM DTT, 3-4 microM RecA) in the absence of ATP. These measurements yield distributions of the translational diffusion coefficients of the changing populations of assembling protein species. Interpretations of results of DLS measurements are made in terms of model hydrodynamic calculations that indicate, under the solution conditions employed, the smallest fundamental quaternary subunit of RecA is a hexamer in a toroidal or lock-washer configuration. Interactions of M13mp19 circular single strand DNA (ssDNA) with RecA assembled to different stages were also investigated. Additions of ssDNA to self-assembled solutions of RecA acts to dissociate the associated structures into hexamer subunits. However, the effect of ssDNA on assembled RecA is highly dependent on the RecA self-assembly state. The longer the assembly time, the less reversible the self-assembled structures of RecA become. Binding isotherms of titrated mixtures of ssDNA with RecA self-assembled to various stages were also determined. Evaluated dissociation constants of RecA/ssDNA complexes were found to increase with increases of the associated state of RecA. These results strongly suggest that, under the solvent conditions employed, the active ssDNA binding form of RecA is a hexamer.

The epidemiology of hearing impairment in an Australian adult population.

BACKGROUND: This study measured the prevalence of hearing impairment, and major demographic factors that influence the prevalence, in a representative South Australian adult population sample aged > or = 15 years. METHODS: The study group was recruited from representative population surveys of South Australians. Participants in these surveys who reported a hearing disability were then recruited to an audiological study which measured air and bone conduction thresholds. In addition a sample of those people who reported no hearing disability were recruited to the audiological study. RESULTS: The data reported in this study are the first in Australia to assess the prevalence of hearing impairment from a representative population survey using audiological methods. The data show that 16.6% of the South Australian population have a hearing impairment in the better ear at > or = 25 dBHTL and 22.2% in the worse ear at the same level. The results obtained in this representative sample compare well with those obtained in the British Study of Hearing, although some differences were observed. CONCLUSIONS: Overall, there are only a few studies worldwide that have audiologically assessed the impairment of hearing from a representative population sample. The overall prevalence of hearing impairment in Australia is similar to that found in Great Britain, although there are some differences between the estimates of severity of impairment and some sex differences. The corroboration of the two studies reinforces the status of hearing impairment as the most common disability of adulthood. The present study also showed that there are a large number of Australians who may benefit from a more systematic community-based rehabilitation programme including the fitting of hearing aids. Secondly, the study identified the need for health goals and targets for hearing to be based on an epidemiological approach to the problem.

Anatomical and physiological assessments of peripheral nerve grafts in the dorsal columns of the spinal cord.

Portions of 1 cm length of the sensory radial nerve from the cat forelimb were used to replace an excised portion of the dorsal columns in the upper lumbar spinal cord. Observations were made on the clinical recovery of the animals, and cine recordings were made of their ability to traverse a horizontal ladder 5 months after the grafting procedure. Evoked sensory potential studies performed 6 months after grafting showed that an impulse arising from a stimulus applied to the sciatic nerve could be recorded in the spinal cord caudal to the graft, in the graft and in the spinal cord rostral to the graft in 5 out of 8 animals. Tracing of nerve connections with injection of horseradish peroxidase into the grafts resulted in labelling of nerve cell bodies in dorsal root ganglia and the grey matter of the lumbar spinal cord up to a distance of 10 mm away from the graft. These results confirm that peripheral nerve grafts can provide a satisfactory environment for the regrowth of ascending fibres in the dorsal columns of the spinal cord. However, there is as yet no evidence that the regenerated fibres succeed in forming useful synaptic connections with other nerve cell bodies.

Prevention of nitroimidazole resistance in Campylobacter pylori by coadministration of colloidal bismuth subcitrate: clinical and in vitro studies.

One hundred patients with duodenal ulceration and Campylobacter pylori in their stomach were entered into a double blind placebo controlled prospective study. Treatment schedules were cimetidine and placebo, or cimetidine and tinidazole, or colloidal bismuth subcitrate (CBS) and placebo, or CBS and tinidazole. Seventeen per cent of isolates of C pylori obtained at the first endoscopy were resistant to tinidazole and 70% of the second isolates from patients given cimetidine and tinidazole became tinidazole resistant. Suspensions of nitroimidazole sensitive cultures of C pylori showed that three of 22 isolates had a nitroimidazole resistant subpopulation. In patients who healed and remained free of C pylori after treatment ulcers recurred less often than in patients who healed but retained C pylori (23% v 73% over 12 months, p less than 0.001).

Response of Campylobacter pyloridis to antibiotics, bismuth and an acid-reducing agent in vitro--an ultrastructural study.

Campylobacter pyloridis was cultured for maximal growth in liquid medium, and effects of exposure to various beta-lactam and macrolide antibiotics, metronidazole, tripotassium dicitrato bismuthane (TDB) and cimetidine were monitored by transmission electronmicroscopy after periods of exposure up to 24 h. With amoxycillin and benzylpenicillin (0.12-1 mg/L) and cephalexin (2 mg/L) the normal bacilliform morphology was replaced by bulging and dumb-bell-like profiles showing cell-wall blebbing and vesiculation, and eventually by swollen forms with incomplete cell walls undergoing lysis. These changes developed progressively between 2 h and 24 h and were accelerated at the higher antibiotic concentrations. Erythromycin and clindamycin caused central clearing, ribosomal coagulation and impaired cross-wall formation. There were no gross structural changes in the presence of metronidazole (4 mg/L), TDB (1000 and 2400 mg/L) or cimetidine (1000 and 2000 mg/L); but with TDB focal accumulation of particulate bismuth complex was detected under the cell wall, affecting nearly all organisms by 24 h. In parallel viability tests, metronidazole and TDB both showed bactericidal activity, but cimetidine did not. These findings support the clinical experience that favours combination therapy with bismuth plus an appropriate systemic antibiotic as the regimen of choice for effective clearance of the organisms in C. pyloridis-associated gastritis.