Protein tyrosine phosphorylation in equine platelets: the effect of stimulation by thrombin and platelet-activating factor (PAF)

Protein tyrosine phosphorylation (PTP) in thrombin- and platelet-activating factor (PAF)-stimulated equine platelet activation was investigated in the absence and presence of 2 protein tyrosine kinase inhibitors (PTKIs), methyl 2,5-dihydroxycinnamate (MDHC) and genistein. Washed equine platelets aggregated irreversibly in response to thrombin or PAF in an agonist concentration dependent fashion. MDHC produced an MDHC concentration and time dependent inhibitory effect on rate and extent of thrombin- and PAF-induced aggregations, whereas the effect of genistein on the same parameters was only genistein concentration dependent. Western blotting demonstrated tyrosine phosphorylated proteins in resting platelets. Changes in the PTP pattern occurred both when platelets were stimulated with varying concentrations of thrombin or PAF for a standard time (3 min) or with a standard agonist concentration (0.17 u/ml thrombin or 10(-10) mol/l PAF) for varying times. Different patterns of PTP were produced by thrombin and PAF. 500 mumol/l MDHC and 300 mumol/l genistein each affected the PTP patterns produced in response to thrombin or PAF, but in different ways. PTP results with thrombin and PAF in the presence of 500 mumol/l MDHC were similar, as were those in the presence of 300 mumol/l genistein. However, there were many differences in the PTP results between thrombin (or PAF) in the presence of MDHC and between thrombin (or PAF) in the presence of genistein. Therefore, although both inhibitors are PTKIs, they have different effects on the PTP induced by either agonist. Our work has produced the first evidence of PTP in equine platelets. It is probable that the changes in PTP are related to events in the signal transduction pathway.

The effects of tyrphostins B42 and B46 on equine platelet function and protein tyrosine phosphorylation.

The effects of the protein tyrosine kinase inhibitors tyrphostins B42 and B46 on equine platelet function and protein tyrosine phosphorylation (PTP) were assessed. Tyrphostins B42 and B46 (both at 100 microM concentration) produced significant inhibition of thrombin-stimulated equine platelet aggregation. The effect of tyrphostin B46 was also time-dependent. The same concentration of these inhibitors produced very little or no inhibition of platelet-activating factor (PAF)-induced aggregation. The effects of tyrphostins B42 and B46 on thrombin- and PAF-stimulated PTP were generally similar, although some bands were more strongly inhibited when thrombin was the agonist. Therefore, although thrombin and PAF both act via G-protein coupled receptors, PAF may be capable of utilising an alternative signal transduction pathway to that used by thrombin.

Assessment of psychiatric morbidity in patients attending a colposcopy clinic situated in a genitourinary medicine clinic.

OBJECTIVE: To determine the adverse psychological implications of referral for colposcopic screening within a genitourinary medicine clinic. DESIGN: Cross sectional survey. SETTING: A colposcopy clinic held within a genitourinary medicine clinic. SUBJECTS: 160 consecutive women referred to the clinic were assessed for psychiatric morbidity using the General Health Questionnaire (GHQ-28). Women were referred to the colposcopy clinic because of one or more of the following: abnormal cervical cytology, condylomata acuminata, HIV antibody positivity. A history of prior local ablative therapy to the cervix was also included in the analysis. RESULTS: There was no difference in psychiatric morbidity, as detected by the GHQ-28, in women referred to the clinic because of abnormal cervical cytology or condylomata acuminata. The total GHQ-28 scores indicated a significant increase in psychiatric morbidity, with increased sub-scores indicating social dysfunction, anxiety and somatic symptoms, in women who had had prior laser therapy to the cervix. Women with HIV infection attending the clinic were noted to have an increase in GHQ-28 sub-scores indicating social dysfunction and depression. CONCLUSIONS: Women who have undergone laser therapy to the cervix may benefit from psychological evaluation and supportive measures if they develop further genital lesions which require colposcopic evaluation. Women with HIV infection need further psychological evaluation prior to planning intervention and preventative strategies.

The role of humoral immunity in Lactobacillus casei cell wall induced arthritis.

Although both cellular and humoral immunity have been shown to play important roles in the development of collagen induced arthritis, their roles in the pathogenesis of bacterial cell wall induced arthritis remain unclear. Previous studies of humoral immunity in bacterial cell wall induced arthritis were carried out in outbred animals and measured the humoral response to only the eliciting bacteria. We compared the humoral immune responses of arthritis susceptible Lewis and arthritis resistant Fisher rats after the injection of arthritogenic group B Lactobacillus casei cell wall fragments. Both strains developed significant IgG and IgM responses to the Lactobacillus casei cell wall fragments. Neither strain developed a significant immune response to types I, II, IX or 1a2a3a collagens. These data suggest that humoral immune responses to the Lactobacillus casei cell wall fragments and types I, II, IX, or 1a2a3a collagens do not play a significant role in determining the differing arthritis susceptibilities of Lewis and Fisher rats.

Penicillamine-induced proteinuria: risk factors.

Twenty-six of 300 patients (9%) with rheumatoid arthritis (RA) developed penicillamine-induced proteinuria. The mean daily dose and duration of therapy at onset of proteinuria were 591 mg and 9 months, respectively, while the mean duration of proteinuria was 5.5 months. However, six patients developed proteinuria at 250 mg/d and six after 9 months of therapy. Twelve patients were successfully either restarted (five) or maintained (seven) on penicillamine with resolution of proteinuria. No permanent renal impairment occurred. Positive risk factors included the presence of HLA-B8 and DR3 and prior gold-induced proteinuria. Patients with prior gold-induced proteinuria should be observed more carefully, but tissue typing is not recommended as proteinuria is reversible. Furthermore, penicillamine can be restarted or maintained in these patients if the RA has responded favorably to the drug.

Parenteral gold therapy in the Felty syndrome. Experience with 20 patients.

Most of the patients with the Felty syndrome suffer from such complications as fevers, infections, cutaneous ulcers, and vasculitis. Unfortunately, there are no therapeutic interventions that are predictably beneficial. We report our experience with 20 patients who received parenteral gold therapy for 2 to 114 months (mean, 23.6 months). All had complications of the Felty syndrome. On parenteral gold therapy, 60% had a complete response, 20% had a partial response, and 20% were unresponsive by preselected criteria. No serious complications were encountered. We think that parenteral gold therapy should be considered early, before other agents, in the treatment of this condition.

Splenic atrophy in systemic lupus erythematosus.

Five of 70 patients with systemic lupus erythematosus seen over a 5-year period had peripheral blood films suggestive of hyposplenism. Technetium-99m-sulfur colloid scans showed no splenic activity in three patients. One of these three patients, who had a spontaneous remission of persistent thrombocytopenia concurrent with the appearance of functional asplenia, had splenic atrophy shown by computed tomography; a second patient, who died of pneumococcal septicemia, was shown to have splenic atrophy with lymphocyte depletion at autopsy. The development of functional asplenia in the third patient has now, to date, had any obvious effect on her disease. In the two patients with normal scans, blood film findings returned to normal with treatment of the underlying disease. Polyvalent pneumococcal vaccine is recommended for patients with lupus erythematosus who have splenic atrophy.

Hyposplenia in a patient with systemic lupus erythematosus.

During the course of systemic lupus erythematosus in a young female patient the peripheral blood smear incidentally showed the features of hyposplenism. Silent lupus vasculitis with splenic infarction was suspected as the cause of this.