Janus kinase 3 (Jak3) is essential for common cytokine receptor gamma chain (gamma(c))-dependent signaling: comparative analysis of gamma(c), Jak3, and gamma(c) and Jak3 double-deficient mice

The common cytokine receptor gamma chain (gamma(c)) is an essential receptor component for IL-2, IL-4, IL-7, IL-9 and IL-15, and thereby gamma(c)-deficient mice exhibit impaired T cell and B cell development. The Janus family tyrosine kinase 3 (Jak3) is known to be associated with gamma(c), and the reported phenotypes of gamma(c)-deficient (gamma(c)(-)) and Jak3-deficient (Jak3(-)) mice are similar, indicating that Jak3 is an essential transducer of gamma(c)-dependent signals. Nevertheless, certain differences have been suggested related to the range of actions of gamma(c) and Jak3. To clarify whether gamma(c)-dependent cytokines can partially transduce their signals without Jak3, we compared lymphocyte development in gamma(c)(-), Jak3(-), and gamma(c) and Jak3 double-deficient (gamma(c)(-)Jak3(-)) mice in the same genetic background. With the exception that T and B cells in Jak3(-) mice express high levels of gamma(c), the defects in thymocyte and peripheral T cell and B cell development are indistinguishable among gamma(c)(-), Jak3(-) and gamma(c)(-)Jak3(-) mice. Interestingly, although Bcl-2 induction was previously suggested to be Jak3-independent, IL-7 cannot induce Bcl-2 expression in CD4 single-positive (SP) thymocytes in either gamma(c)(-) or Jak3(-) mice nor can IL-7 rescue CD4 SP thymocytes from dexamethasone-induced cell death in gamma(c)(-) or Jak3(-) mice. These results indicate that Jak3 is absolutely essential for gamma(c)-dependent T cell and B cell development, and for gamma(c)-dependent prevention of thymocyte apoptosis.     

Lymphocytes expressing alpha1beta1 integrin (very late antigen-1) in peripheral blood of patients with arthritis are a subset of CD45RO(+) T-cells primed for rapid adhesion to collagen IV

We report that very late antigen-1 (VLA-1(+)) CD3(+)CD45RO(+) T-cells are selectively segregated from VLA-1(-) peripheral blood (PB) mononuclear cells (MC), in which CD3(+) T-cells are evenly CD45RO(+) and CD45RO(-), when PBMC are stained with a monoclonal antibody (mAb) to VLA-1 and passaged on immunomagnetic columns. In contrast, both VLA-1(+) and VLA-1(-) MC isolated from synovial fluid (SF) are mainly CD45RO(+)CD3(+) T-cells. VLA-1(+) MC formed 13 +/- 5.3% of MC eluting from columns loaded with PBMC of patients with seropositive rheumatoid arthritis (n = 6) and 2.3 +/- 1.6% of patients (n = 4) with other arthritides (P < 0.022). Importantly, only the VLA-1(+) MC from PB and SF adhered to collagen IV upon triggering with phorbol 12-myristate 13-acetate. Moreover, adhesion and migration on collagen IV were preferentially maintained in lines cultured from VLA-1(+) T-cells, and both were inhibited by mAb to the VLA-1 alpha1 I domain. These results suggest that VLA-1(+) CD45RO(+) T-cells in patients with arthritis could play a role in both systemic and local inflammation by rapidly adhering to collagen IV.     

A report on 100 cycles of oocyte donation; factors affecting the outcome

Eighty-two patients had 100 cycles of oocyte donation from 68 donors resulting in 27 clinical pregnancies. The source of donated oocytes was 42 fertile volunteers and 26 patients from the assisted conception programme. The pregnancy rate was significantly higher when intra-Fallopian transfer was performed (36%; 21/59), compared with intrauterine transfer (15%; 6/41). The pregnancy rate following fresh gamete/embryo transfer (39%; 15/39) was slightly higher than for frozen embryo transfer (20%; 12/61). The age of the recipient significantly affected the pregnancy rate. The pregnancy rate was 50% in the 25-29 years age group and steadily dropped to 9.7% in the 45-49 age group. The pregnancy rate in patients with primary ovarian failure (50%; 8/16) was significantly higher than in patients with secondary ovarian failure (18%; 9/50). The pregnancy rate was significantly greater when parous donors (33%; 23/69) were used compared with non-parous donors (13%; 4/31). The number of gametes/embryos transferred significantly affected the pregnancy rate regardless of the treatment used. If one or two gametes/embryos were transferred, the pregnancy rate was 11% compared with 33% if three to four embryos were transferred. The age of the donors did not affect the pregnancy rate. The majority of the donors were under the age of 35 years. The best results (50% per cycle) were therefore achieved using gametes from parous donors and transferring three to four oocytes fresh to the Fallopian tubes of a young recipient.     

Computerized family practitioner committee records — a data base for general practitioners

In the primary care environment the role of preventive medicine is assuming increasing importance and general practitioners need accurate and up-to-date information about their practice population. Computerization of family practitioner committee registers should provide a readily accessible data base from which data about groups of patients within the practice area can easily be extracted. This paper describes a study carried out in Northumberland, which set out to establish the type of information which would be of interest to general practitioners and how it could be produced.

It was found that a data base holding only registration data was of limited value to general practitioners, although useful for identifying target groups for screening programmes and showing demographic trends within the practice. The doctors felt that the inclusion of medical data would make the register a far more effective resource.

     

Different Chinese hamster cell lines express a G1 period for different reasons

Previous studies from our laboratory have shown that the absence of G1 (G1^– condition) in two lines of Chinese hamster cells is dominant over the presence of G1 (G1⁺ condition) in a variety of intraspecific cell hybrids. G1⁺ mutants or variants can be isolated from G1^– cells following mutagenesis and selection. These G1⁺ mutants fall into multiple complementation groups based on their abilities to form G1^– cell hybrids with one another. This is evidence that different mutants have G1 intervals for different reasons, possibly as the result of deficiencies in functions necessary for G1^– cell cycles. In this report we have used cell hybrid analysis to ask whether cells of different, naturally occurring G1⁺ lines of Chinese hamster are able to complement to produce G1^– hybrids. We have found three complementation groups among the four G1⁺ cell lines examined. Therefore, these lines define three different reasons or bases for the existence of a G1 interval. These results lead us to suggest that multiple requirements must be met for these cells to start the S period, but that failure to fulfill only a single and different requirement is responsible for the presence of a G1 interval in any given cell line.     

Evidence from twins for acquired cellular immune hyperactivity in type 1 diabetes

Type 1 diabetes has been associated with an increased frequency of activated T cells and T-cell hyperactivity to non-specific and disease-specific stimuli including the islet autoantigen glutamic acid decarboxylase 65 (GAD). To address whether T-cell hyperactivity is genetic or acquired we measured whole blood cytokines in vitro in response to GAD or tetanus in 18 identical twin pairs, nine discordant for type 1 diabetes. In addition, the activity of 2', 5' oligoadenylate synthetase (OAS) in blood mononuclear cells was measured as a marker of viral infection. Interleukin-2 (IL-2) basally and IL-2 and interferon-gamma (IFN-gamma) in response to GAD, were detected more frequently and at higher levels in diabetic compared to non-diabetic twins. IL-10 was not different between groups. OAS activity was increased in diabetic compared to non-diabetic twins and showed a correlation with basal IL-2 and GAD-stimulated IFN-gamma and IL-10. These findings suggest that T-cell hyperactivity in type 1 diabetes is an acquired trait and could reflect persisting virus expression.     

Distribution of neurotensin binding sites in rat brain: a light microscopic radioautographic study using monoiodo [125I]Tyr3-neurotensin

The topographic distribution of specifically labeled neurotensin binding sites was examined by light microscopic radioautography in rat brain sections incubated with monoiodo [125I]Tyr3-neurotensin. Preliminary experiments indicated that under the present experimental conditions [125I]neurotensin specifically binds to a single apparent population of sites with a dissociation constant of 7.7 +/- 0.3 nM, and that fixation of the labeled sections with glutaraldehyde ensures regionally proportional retention of more than 70% of bound [125I]neurotensin molecules. High concentrations of [125I]neurotensin binding sites were detected in the olfactory bulb and tubercle, parts of the neocortex, the lateral septum, the diagonal band of Broca, the caudate putamen, the amygdala, the dentate gyrus, the anterior dorsal nucleus of the thalamus, the suprachiasmatic nucleus of the hypothalamus, the medial habenula, the zona incerta, the substantia nigra and the ventral tegmental area. In certain areas, such as in the diagonal band of Broca, the substantia innominata, the nucleus basalis and the pars compacta of the substantia nigra, discrete accumulations of silver grains were apparent over neuronal perikarya and their proximal dendrites. In most areas, however, the label appeared more or less uniformly distributed over nerve cell bodies and surrounding neuropil. In several instances, the labeling conformed with the distribution of cell bodies of origin and terminal aborizations of specific projection systems, suggesting that neurotensin receptors might be distributed both proximally and distally on the plasma membrane of certain neurons. Such putative "neurotensinoceptive" projection systems might involve part of the mesostriatal, mesocortical and mesolimbic dopamine systems, as well as the raphe-prosencephalic serotonin system and the habenulo-interpeduncular and basal forebrain-cortical cholinergic systems. Finally, areas of dense [125I]neurotensin labeling often corresponded to zones previously shown to exhibit intense acetylcholinesterase staining, suggesting the existence of a possible link between the expression of neurotensin binding sites and that of acetylcholinesterase in certain neuronal populations.     

Developmental changes in the astrocytic response to lateral olfactory tract section

When the lateral olfactory tract (LOT) of the golden hamster, Mesocricetus auratus, is transected in the first week of postnatal life, axons can grow back past the lesion and achieve functional reinnervation of caudal projection regions. In contrast, when the tract is sectioned after postnatal day 7 (P7), axons do not reinnervate regions caudal to the cut. The experiments reported here investigated whether regenerative failure after tract section in pups older than P7 is accompanied by developmental changes in the astrocytic response. LOT transections were performed at P3 and P9 and the glial reaction was observed at survival times ranging from 12 hr to 2 weeks. Immunocytochemistry with glial fibrillary acidic protein (GFAP) was employed for histological visualization of astrocytic reactivity. Staining for GFAP immunoreactivity showed an appreciable glial reaction after tract section at both P3 and P9, but the extent of astrocytic hypertrophy and proliferation of glial processes was considerably greater and more extensive after tract section at P9. Radial glial cells were observed 2 weeks after LOT transection at P3 but were absent after lesions made at P9. The results from this study suggest that the developmental loss of regenerative capacity after LOT transection may be related to maturational changes in the glial response. In particular, the presence of radial glial elements after P3 lesions could serve to establish a more favorable microenvironment for axonal elongation.     

Role of the common cytokine receptor gamma chain (gammac) in thymocyte selection

During thymocyte development, T-cell receptor (TCR) alphabeta-mediated intracellular signals can elicit two entirely different cellular responses: positive selection (resulting in rescue from death and maturation or differentiation) and negative selection (induction of apoptosis). Here, Hiroshi Nakajima and colleagues discuss how survival signals that are dependent on the common cytokine receptor gamma chain (gammac) might affect the TCR-driven selection process in thymocytes, underscoring the potential role of cytokines in this process.