Interactions of human nuclear proteins P1Mcm3 and P1Cdc46

Human nuclear proteins P1Mcm3 and P1Cdc46 have high sequence similarities with the corresponding yeast proteins known to be required for the initiation of genome replication. Nuclei of proliferating HeLa cells contain relatively high amounts of P1Mcm3 (about 10(6) molecules/nucleus) of which only a small fraction is bound to a nuclear structure, most probably chromatin. At 0.5 M NaCl, the structure-bound nuclear protein can be partially solubilized as a dimer composed of P1Mcm3 and the related protein P1Cdc46. However, most protein P1Mcm3 is not bound to a nuclear structure and appears in the nucleoplasm. About 10% of protein P1Mcm3 in the soluble fraction is free and uncomplexed, and the remaining P1Mcm3 forms stable complexes with protein P1Cdc46. These P1Mcm3/Cdc46 complexes occur as dimers and in high-molecular-mass complexes (approximately 500 kDa). The high-molecular-mass complexes dissociate in 0.5 M NaCl and release P1Mcm3/Cdc46 dimers. It has frequently been proposed that the Mcm proteins may function as licensing factors for genome replication. Our data imply that the active form of an Mcm protein is not a monomer, but a protein complex that includes an Mcm3/Cdc46 dimer. DNA polymerase alpha is not a component of this complex.

The P1 family: a new class of nuclear mammalian proteins related to the yeast Mcm replication proteins

Monospecific antibodies against an oligopeptide, conserved among the Mcm class of yeast replication proteins, were used to screen a human cDNA library. Eight of the isolated cDNA clones have the potential to code for sections of proteins with high sequence similarities to the yeast proteins Mcm3 and Cdc46 from Saccharomyces cerevisiae and Cdc21 from S. pombe. Our results establish a novel and highly conserved family of nuclear proteins in mammalian cells.

The papal chase. The Pope's visit: a "mass" gathering

When Pope John Paul II visited Denver, CO, in August, members of the city's EMS community volunteered to provide coverage at special events. But no one anticipated the tens of thousands of medical emergencies that occurred, overwhelming EMS resources. In this special feature, Dottie Schulte, RN, MS, and Denis M. Meade, EMT-P, offer a behind-the-scenes look at how EMS professionals coped during the unprecedented religious experience.

Cycloheximide inhibits cellular, but not SV40, DNA replication

We have prepared extracts from cycloheximide-treated cells for the study of simian-virus-40 (SV40)-DNA replication in vitro. When supplemented with the viral initiator protein (large T antigen), these extracts fully supported SV40-DNA replication. We also determined that SV40-DNA replication in vivo is much more resistant to cycloheximide than cellular DNA replication. SV40 encodes its own initiator protein, T antigen, which also functions as a DNA helicase, but depends on cellular functions for all additional replication reactions. Therefore, it appears to be quite likely that cycloheximide affects cellular DNA replication by blocking the synthesis of (a) cellular function(s) that is(are) performed by T antigen in SV40-DNA replication. Indeed, DNA fiber autoradiography and alkaline sucrose gradient centrifugation of pulse-labeled cellular DNA showed that cycloheximide treatment almost completely suppressed replicon initiation and reduced the rate of replication fork movement to about one third of the control.

Patterns of neoplasia in c-mos transgenic mice and their relevance to multiple endocrine neoplasia

We have previously described a neurological phenotype for transgenic mice carrying the c-Mos proto-oncogene. Pheochromocytomas and C-cell thyroid neoplasms occur in these transgenic lines in patterns that are similar to those seen in multiple endocrine neoplasia type 2 (MEN 2). Characterization of the pathological lesions via immunohistochemistry underscores similarities between MEN 2 and these transgenic mice. When transgenic mice that do not display the MEN 2 phenotype are crossed to a different background, the progeny display the MEN 2 phenotype. Thus the interaction of the background with the transgene is such that it can suppress tumor information. This observation bears special relevance to the human syndrome in that this model system may be used to study the question of penetrance of phenotype.

Thin filament changes during in vivo rat heart development

Developmental differences in myocardial performance are known to exist. It is likely that the profile of protein isoforms present on the developing thin filament contributes to these observed differences. We have prepared thin filaments from developing and mature rat hearts by using an immunoprecipitation procedure developed in our laboratory. Analysis of these isolated thin filaments by Western immunoblots and two-dimensional gel electrophoresis demonstrates troponin I and troponin T isoform switching on the developing thin filament. Troponin I isoform switching begins by embryonic d 18 and is complete before the 3rd postnatal wk. Troponin T isoform switching begins between embryonic d 18 and birth and is complete between the 2nd and 3rd postnatal wk. The degree of phosphorylation of tropomyosin in thin filaments appears to be developmentally regulated, decreasing with advancing age. Nonmuscle isoforms of tropomyosin are also detectable in thin filaments from developing and mature rat hearts. These phenomena (troponin isoform switching, the degree of phosphorylation of tropomyosin, and the presence of nonmuscle isoforms of tropomyosin on cardiac thin filaments) likely play a role in the function of immature thin filaments and in the assembly of mature thin filaments.

[Musculoskeletal manifestations in patients after bone marrow transplantation. Initial clinical rheumatologic observations]

From January 1986 through January 1989 69 adult patients received bone marrow transplants--20 with autologous, and 49 with allogeneic bone marrow. Ten patients after autologous and 33 patients after allogeneic transplantation (TX) could be examined for rheumatological complaints. None of the patients after autologous TX displayed rheumatological manifestations; 8/33 patients after allogeneic TX developed bone necrosis and they had to be treated for several months with high daily doses of prednisolon (mean: 55 mg/day). In 18/33 patients an oligoarthropathy of large joints could be observed after a significant reduction of prednisolon dosage over a period of 5 months. In addition 15/18 of these patients later developed a chronic g-v-h-disease. The TX arthropathy may be induced by cortico-steroid therapy (resp. reduction), but most important, it is a clinical sign for an imminent chronic g-v-h-disease.

Pressure induced hypertrophy in the hearts of growing dwarf pigs

The left ventricles of 8 sibling dwarf pigs were stressed by banding the aorta ascendens for 7 to 49 days. There was no developmental retardation. Neither light nor electron microscopic controls showed signs of insufficiency. 3.7 X 10(7) Bq/kg (1 mCi/kg) body weight (3 H-)methyl thymidine had been applied as pulse at the end of the experiment. The 3 H-index (LI) of the left ventricular wall increases with the pressure registered (r = 0.95). At the same time the values for the right ventricular wall and the left atrium showed an inverse tendency corresponding to the fact that all indices decrease during normal growth. The relation of the indices is two to one for each atrium and its corresponding ventricle, as well as for the stressed left ventricular wall to the right one. The 3 H marked cells are found in groups with constant distances (75-85 microns). High LI are the consequences of the enlargement of these groups. There is no detectable relation to an anatomic structure. Some rare mitoses could be seen, especially in the left ventricular wall. Signs of a high biochemical activity are accumulations of mitochondria, high number of polysomes and large Golgi areas as well as laminas of ergastoplasm. The nuclei are extremely invaginated.

Field replication of classwide peer tutoring

We conducted a large-scale field replication study of classwide peer tutoring applied to spelling instruction (Greenwood, Delquadri, & Hall, 1984). Two hundred and eleven inner-city students in four schools participated during their first- and second-grade school years. The effects of classwide peer tutoring were compared to teacher instructional procedures and pretest probes using a group replication design (Barlow, Hayes, & Nelson, 1984). Analysis of group and individual results indicated that (a) both teacher instructional procedures and classwide peer tutoring were effective in increasing spelling performance above pretest levels, (b) peer tutoring produced statistically greater gains relative to the teachers' procedures for both low and high student groups formed on pretest levels, (c) these outcomes were representative of groups, classes, individuals, and years during the project, and (d) participant satisfaction with the program was generally high. A separate analysis of the social importance of treatment outcome revealed differential findings for low and high groups related to pretest levels. Implications of these findings are discussed.

Redefinition of school nursing practice: integrating the developmentally disabled

Results of three needs assessment studies which had the purpose of providing direction for school nursing practices which would address some of the unmet health needs of today's children and adolescents are reported. Results provide specific examples of how school nurses have not been meeting school health needs through an analysis of one specific need -- integrating the developmentally disabled into the regular school setting. Data were collected from parents, teachers and other supportive personnel in schools by interview and survey methods. Environmental assessments were conducted and the policies and procedures governing health-related activities required by special need students were reviewed. The data indicated that for developmentally disabled students, nurses were not performing the commonly accepted functions of nursing and were not transposing their knowledge of the components of health care ordinarily provided in health care settings to care provided in nontraditional health care settings. Examples of nursing functions and the activities needed to fulfill those functions are provided.

A test of the Broen-Storms theory of cognitive deficit in schizophrenia

Broen and Storms have developed a popular behavioristic theory to explain schizophrenic thought disorder. It holds that thought disorder results from schizophrenics' having higher drive levels and lower response-strength ceilings than non-schizophrenics. As a result, the strength of appropriate (usually strong) responses is rivaled by that of inappropriate, ordinarily-weak responses. This, in Broen and Storms' theory, is the cause of disorganized, schizophrenic behavior. We tested several hypotheses derived from Broen and Storms' assumptions that schizophrenics have higher drive and lower response strength ceilings than controls in a paired-associates learning study. We did not find support for our hypotheses that schizophrenics would show better early-trials learning than controls, that a presumably drive-inducing threat of pain would enhance early trials learning in schizophrenics or controls, that either threat of pain or schizophrenia would be associated with a low learning asymptote, or that either the positive or negative effects of pain would be accentuated in schizophrenics. The results did not support the theory.

Responses of high- and low-emotional deficit patients to exciting, grating, and neutral stimuli

The preferences of high- and low-anhedonia and sensation-seeking psychiatric hospital groups for music rated as exciting, grating, and neutral, and the tendencies of these groups to modify the volume level at which they were exposed to these pieces, were compared. Volume-level choice was unrelated to anhedonia and sensation-seeking, which casts doubt on the theory that these affective deficits are mediated by efforts to reduce the quantity of incoming emotional stimulation. Anhedonia scores were not related to preferences for the three types of music. However, in contrast to high sensation-seekers, low sensation-seekers tended to dislike all types of music, and especially those rated as grating.