A dibasic motif in the tail of a class XIV apicomplexan myosin is an essential determinant of plasma membrane localization.

Obligate intracellular parasites of the phylum Apicomplexa exhibit gliding motility, a unique form of substrate-dependent locomotion essential for host cell invasion and shown to involve the parasite actin cytoskeleton and myosin motor(s). Toxoplasma gondii has been shown to express three class XIV myosins, TgM-A, -B, and -C. We identified an additional such myosin, TgM-D, and completed the sequences of a related Plasmodium falciparum myosin, PfM-A. Despite divergent structural features, TgM-A purified from parasites bound actin in an ATP-dependent manner. Isoform-specific antibodies revealed that TgM-A and recombinant mycTgM-A were localized right beneath the plasma membrane, and subcellular fractionation indicated a tight membrane association. Recombinant TgM-D also had a peripheral although not as sharply defined localization. Truncation of their respective tail domains abolished peripheral localization and tight membrane association. Conversely, fusion of the tails to green fluorescent protein (GFP) was sufficient to confer plasma membrane localization and sedimentability. The peripheral localization of TgM-A and of the GFP-tail fusion did not depend on an intact F-actin cytoskeleton, and the GFP chimera did not localize to the plasma membrane of HeLa cells. Finally, we showed that the specific localization determinants were in the very C terminus of the TgM-A tail, and site-directed mutagenesis revealed two essential arginine residues. We discuss the evidence for a proteinaceous plasma membrane receptor and the implications for the invasion process.

Core outcomes measures for inguinal hernia repair.

BACKGROUND: Demands on the medical profession to develop performance measures and demonstrate cost-effectiveness make it imperative that a uniform approach to the measurement of outcomes for common conditions be adopted. We report here on patient acceptance, response rates, and utility of a new set of core outcomes measures for patients with inguinal hernia (IH), which incorporates patient reporting of outcomes. METHODS: Beginning in March 1994, a convenience sample of patients scheduled for IH repair completed a series of questionnaires addressing a range of patient case mix and outcomes dimensions, including demographics, comorbid conditions, SF-36 health status (Medical Outcomes Study 36-item short-form health survey), and condition-specific questions, expectations, and responses to the surgical experience before and after operation. Surgical data were abstracted from the medical records. RESULTS: One hundred three patients were entered in the study; 63 completed 2-month reports and 44 completed 6-month reports. Acceptance of the study and response rates were excellent. Differences in health status associated with IH have been identified in two SF-36 domains, and changes in function after repair noted in several others, supporting the applicability of this measure. Outcomes may also differ by type of hernia and type of repair performed. CONCLUSIONS: A core outcomes measurement set for IH that encompasses demographics, comorbidities, health status, expectations, utilization, and condition-specific data provides a portrait of patient outcomes that is useful to providers and patients, and combined with cost and satisfaction data, it can be used for benchmarking and improving surgical care.

Assessment of patient outcomes after operation for primary hyperparathyroidism.

BACKGROUND: We have used the SF-36, an accepted health status assessment tool, in conjunction with condition-specific clinical information, to assess patient-reported health status before and after operation for primary hyperparathyroidism (1 degree HPT). METHODS: Beginning in March, 1994, a convenience sample of patients has been asked to complete the SF-36 and provide additional demographic and condition-specific information for study. The SF-36, which measures eight components of functional status and well-being, is completed in person before operation and again by mail at 2 and 6 months after operation. Clinical and condition-specific data are gathered at the same times. RESULTS: Fifty-nine patients have entered the study; 56 had abnormal parathyroid tissue removed. Patients with 1 degree HPT have lower SF-36 scores in all health domains at baseline than do healthy patients. At 2 months, scale scores for emotional role limitations and bodily pain improved by more than 10 points. At 6 months all eight scale scores showed improvement, seven of eight by 10 points or more. Commensurate improvements in HPT-specific measures were also seen. CONCLUSIONS: Patient-reported measurements of health outcomes after parathyroidectomy for 1 degree HPT show improvement in all aspects of health status 6 months after operation. Most dramatic improvements were reported in reduction of bodily pain and in improved vitality and emotional and physical function. Surgical correction of 1 degree HPT improves patient health status and quality of life.