Expression of the murine plasma cell nucleotide pyrophosphohydrolase PC-1 is shared by human liver, bone, and cartilage cells. Regulation of PC-1 expression in osteosarcoma cells by transforming growth factor-beta.

A bone and cartilage enzyme with both 5'-nucleotide phosphodiesterase I and nucleotide pyrophosphohydrolase (NTPPPH) activity modulates physiologic mineralization and pathologic chondrocalcinosis by generating inorganic pyrophosphate. We hypothesized that, as for alkaline phosphatase, expression of an NTPPPH gene can be shared by cells from bone, cartilage, and liver and by certain leukocytes. Recently, we demonstrated the hepatocyte and murine plasma cell membrane glycoprotein PC-1 to have both 5'-nucleotide phosphodiesterase I and NTPPPH activity. We detected polypeptides cross-reactive with PC-1 in human U20S osteosarcoma cells, articular chondrocytes, homogenized human knee cartilages, human knee synovial fluids, hepatoma cells, and murine plasmacytoma cells. Constitutive low abundance PC-1 mRNA expression was detected in U20S cells and chondrocytes by a nested RNA-PCR assay and by Northern blotting. TGF beta is known to substantially increase NTPPPH activity in primary osteoblast cultures. We demonstrated that TGF beta 1 increased NTPPPH activity and the level of PC-1 mRNA and immunoprecipitable [35S]-methionine-labeled PC-1 polypeptides in U20S cells. The identification of PC-1 as an NTPPPH expressed in cells derived from bone and cartilage may prove useful in furthering the understanding of the role of NTPPPH i n physiologic and pathologic mineralization.

Methylthioadenosine phosphorylase cDNA transfection alters sensitivity to depletion of purine and methionine in A549 lung cancer cells.

Methylthioadenosine phosphorylase (MTAP), an enzyme involved in purine and methionine metabolism, is present in all normal tissues but is frequently deficient in a variety of cancers. It has been suggested that this metabolic difference between normal and cancer cells may be exploited to selectively treat MTAP-negative cancers by inhibiting de novo purine synthesis and by depleting L-methionine. However, these therapeutic strategies have only been tested in naturally occurring MTAP-positive and -negative cell lines, which might have additional genetic alterations that affect chemotherapeutic sensitivity. Therefore, it is of importance to examine the feasibility of enzyme-selective treatment using paired cell lines that have an identical genotype except for MTAP status. MTAP-negative A549 lung cancer cells were transfected with eukaryotic expression vectors encoding MTAP cDNA in sense and antisense orientations. The resultant stable transfectomas were treated with inhibitors of de novo purine synthesis such as methotrexate, 5,10-dideazatetrahydrofolate, and L-alanosine and by methionine depletion. The A549 cells transfected with an antisense construct (antisense transfectoma) expressed no MTAP protein and were more sensitive to both purine and methionine depletion than were cells expressing MTAP protein (sense transfectoma). Methylthioadenosine was able to completely rescue the sense transfectoma but not the antisense transfectoma from growth inhibition by depletion of purine and methionine. These results prove that MTAP deficiency contributes directly to the sensitivity of cancer cells to purine or methionine depletion. Inhibition of de novo purine synthesis, combined with methionine depletion in the presence of methylthioadenosine, is a highly selective treatment for MTAP-negative cancers.

A methylthioadenosine phosphorylase (MTAP) fusion transcript identifies a new gene on chromosome 9p21 that is frequently deleted in cancer.

Homozygous deletions of human chromosome 9p21 occur frequently in malignant cell lines, and are also common in primary gliomas, lung cancers, and leukemias. Moving from the centromere to the telomere, this complex region encodes the tumor suppressor genes p15INK4B (CDKN2B), p14ARF, p16INK4A (CDKN2A), and the housekeeping gene methylthioadenosine phosphorylase (MTAP). However, not all chromosome 9p21 deletions in tumors include these tumor suppressor genes. Here we describe the partial sequence and the exact localization of a new gene on chromosome 9p21 centromeric of p15INK4B, that formed an in frame fusion transcript with MTAP in a glioma xenograft, and that is homozygously deleted in various malignant cell lines. Northern blot revealed corresponding 1.5 kb transcript in non-deleted cell lines as well as in normal lymphocytes. Using a RNA master blot membrane including 50 different tissues, we could show that this new transcript is expressed in all tissues of the adult but not or only at very low levels in most of the fetal tissues tested. The expression pattern is similar to that of p16INK4A. The localization as well as the deletion pattern makes this transcript a candidate for a new tumor suppressor gene.

Homozygous deletions of methylthioadenosine phosphorylase (MTAP) are more frequent than p16INK4A (CDKN2) homozygous deletions in primary non-small cell lung cancers (NSCLC).

Homozygous deletions of the tumor suppressor gene p16INK4A and deficiency of methylthioadenosine phosphorylase (MTAP), both located on chromosome 9p21, have been independently reported in non-small cell lung cancer (NSCLC). To determine the frequency of co-deletion of these two genes, we investigated 50 samples of primary NSCLC using a quantitative PCR-ELISA. All specimens were fixed in formalin, paraffin embedded and stored until assayed. Histologic subtypes included 25 adenocarcinomas (50%), 21 squamous cell carcinomas (42%) and four large cell carcinomas (8%). Homozygous deletions of MTAP exon 8 could be detected in 19 of 50 NSCLC samples (38%). Adenocarcinoma (11 of 25, 44%) showed a higher deletion frequency than squamous cell carcinoma (six of 21, 29%). In contrast, homozygous p16INK4A deletions were detected in only nine of 50 (18%) samples using specific primers for p16INK4A exon 1alpha. No difference between the histological subtypes and p16INK4A deletion frequency was observed. We further investigated the ten samples with MTAP deletions but intact p16INK4A exon 1alpha with primers specific for p16INK4A exon 3, the exon nearest to MTAP exon 8. Interestingly, none of the ten samples had deletion of the p16INK4A exon 3 coding region. Fine mapping analysis performed in ten samples showed a frequent breakpoint between MTAP exon 4 and exon 5. In addition, p16 protein expression could not be detected in five out of six samples with intact p16 but deleted MTAP locus. These data show a high frequency of homozygous MTAP deletions in NSCLC which is associated with detectable co-deletion of p16INK4A in only half of the cases. This result suggests the existence either of another tumor suppressor gene telomeric of p16INK4A or of deletions involving 3'-untranslated (3'-UTR) regulatory regions of p16INK4A that can interfere with its expression or function.

Simulating policy options for psychiatric care in general hospitals under Medicare's PPS.

Psychiatric hospitals and certain distinct part psychiatric units of general hospitals are currently exempt from diagnosis related group (DRG)-based payment under Medicare's prospective payment system (PPS), in large part due to concern about the degree to which such payment would match historical costs for these facilities. This communication simulates DRG-based payments for psychiatric admissions to general hospitals under the PPS and also under a modified version of the PPS. Two major types of modifications are made: (1) an increase in the role of outlier payments and (2) a restructuring of the DRG classification to allow for a difference in the basic payment rate, depending on whether or not care is provided in a facility that is currently exempt. When compared with cost data from just before the start of the PPS, the simulation results show the degree to which these hypothetical modifications will decrease the systematic risk of general hospitals with exempt units from receiving payments that fall short of costs.

Costs of mandates for outpatient mental health care in private health insurance.

Various methods for estimating the cost of mandated mental health benefits have been devised, each resulting in substantially different estimates. These methods neglect to distinguish between the two components of cost to the insurer: social cost (due to increased utilization) and shifted cost (from other sources of payment). We apply a method we developed for estimating the two types of costs of mandates for outpatient mental health services that integrates data from insurers with information from the literature on financing of mental health services. We applied our method to legislation recently proposed in Massachusetts that would double the mandated minimum benefit level from +500 to +1,000. We expect payments by the largest carrier in the state to increase by a factor of 1.65. More than half of this increase represents shifted costs rather than new costs to society.

An analysis of DRG-based reimbursement for psychiatric admissions to general hospitals.

The authors analyzed the potential financial impact of paying general hospitals on the basis of diagnosis-related groups (DRGs) for Medicare alcohol-drug abuse and psychiatric admissions. Average costs per admission were substantially higher for general hospitals with special psychiatric units that are currently exempt from the prospective payment system (PPS) than for hospitals without exempt units. Simulations of DRG-related payments indicated that these payments would be greater for admissions to hospitals with exempt psychiatric units than for admissions to hospitals without exempt units. However, the differences in costs between these two types of facilities were greater than the differences in payments that would occur under a PPS.

Access for low-income children: is health insurance enough?

OBJECTIVE: The Balanced Budget Act of 1997 authorizes $20 billion for states to expand health insurance coverage among uninsured low-income children. This study identifies lessons learned from the Medicaid Extension Demonstration, which was authorized by Congress to experiment with innovative approaches to providing health care coverage for low-income children. The three programs compare and contrast a variety of features that may enhance or detract from access, including a traditional Medicaid expansion, a private indemnity model, and a comprehensive managed care delivery system. METHODOLOGY: Two waves of telephone surveys were conducted with a sample of parents of children participating in the Medicaid Extension Demonstration, and a comparison group of parents of children who were eligible but not participating. Descriptive and multivariate analyses were conducted to determine the impact of the demonstration on access to care. RESULTS: Compared with those who were uninsured, children in the managed care program were more likely to have a medical home and a physician visit and were less likely to have an emergency room visit, and had lower levels of unmet need. Outcomes across the other two demonstration programs were less favorable. CONCLUSIONS: This study suggests that simply providing a Medicaid card or private indemnity insurance card is not enough to ensure access to care. Future initiatives also need to consider the structure of the delivery system, especially the availability of a medical home (with adequate after-hours care), as well as the impact of discontinuous insurance coverage on access to and continuity of care.

Isolation of a thymidine kinase negative mutant of Nocardia lactamdurans.

By selection for resistance to fluorodeoxyuridine in a fluorouracil/fluorouridine resistant background, we have isolated a thymidine kinase negative mutant of Nocardia lactamdurans. This strain is characterized by the inability to incorporate exogenous [2-14C]-thymidine into DNA. The incorporation of radioactive thymine is similarly reduced even in the presence of deoxyadenosine. This phenotype is readily explained by the inability to detect the enzyme thymidine kinase in crude extracts.

Promises unfulfilled: implementation of expanded coverage for the elderly poor.

OBJECTIVE: To examine implementation of the Qualified Medicare Beneficiary (QMB) and Specified Low-Income Medicare Beneficiary (SLMB) programs, enacted in 1988. The article summarizes the origin of the QMB and SLMB programs, describes what we have learned about QMB and SLMB enrollment in state Medicaid programs and, despite some encouraging news on the federal front, identifies policy issues that remain in assuring access to health care for the low-income elderly. SOURCE: Based in part on research that assessed state variations in Medicaid QMB and SLMB enrollment of low-income Medicare beneficiaries and identified best practices among states in administration of the QMB and SLMB programs. STUDY DESIGN: Telephone interviews were conducted with officials in ten states to elicit qualitative information about how state Medicaid programs have implemented federal protections for low-income Medicare beneficiaries. PRINCIPAL FINDINGS: The QMB and SLMB programs fail to reach a sizable proportion of potentially eligible individuals in most states. Fragmentation of Medicare and Medicaid benefits, complex Medicaid eligibility and income verification processes, and rigid federal and state administrative and data systems, impede efforts to achieve promised protection for low-income elderly persons. CONCLUSIONS: For low-income Medicare beneficiaries, obtaining financial protection against their high out-of-pocket health care costs remains an important issue. The complexities associated with aligning Medicare and Medicaid to deliver health benefits to low-income older persons makes improved coordination across federal and state agencies uncertain.

Access and satisfaction within the disabled Medicare population.

Little is known about variations in the levels of access and satisfaction within the disabled Medicare population. Based on the Medicare Current Beneficiary Survey (MCBS), beneficiaries under 65 years of age were classified by original reason for disability (mental versus physical). Those with a mental disability were less likely to have a private physician as a usual source; were less satisfied with the overall quality of care, availability of after-hours care, followup care, and coordination of care; and were more likely to report unmet need, owing in large part to supply barriers. Implications for the current delivery system and for design of managed care programs are discussed.

Access to care in rural America: impact of hospital closures.

This article employs a quasi-experimental, pre/post comparison group design to determine whether rural hospital closures (n = 11) have had a detrimental impact on access to inpatient and outpatient care for the Medicare population. Closure areas experienced a significant decrease in medical admissions, although admission rates remained higher than in comparison areas. Physician services were not found to substitute for inpatient services following a closure. No adverse impacts on mortality were observed. Patients in closure areas were more likely to be admitted to urban teaching hospitals following the closure of their local hospital.

Trends in Medicare Part B mental health utilization and expenditures: 1987-92.

This article examines the impact of expanding Medicare Part B coverage of mental health services, based on analysis of 6 years of Medicare Part B claims data (1987-92). Inflation-adjusted per capita spending more than doubled (from $9.91 to $21.63) following the elimination of the annual outpatient treatment limit and extension of direct reimbursement to clinical psychologists and social workers. There was a 73-percent increase in the user rate (from 23.25 to 40.20 per 1,000 Medicare beneficiaries), and a 27-percent increase in the average number of services per user (from 8.9 to 11.3). Mental health spending increased from 1 percent to 2 percent of expenditures for Part B professional services. Ongoing monitoring of mental health utilization is desirable to ensure that recent access gains are not eroded with the increasing shift to managed care and implementation of gatekeeper mechanisms.

Physician participation in alternative health plans.

In this article, physician participation in alternative health plans is examined, using cross-sectional data from the Physicians' Practice Costs and Income Survey, 1983-85. Overall, about one-third of physicians participated in one or more plans, ranging from 18 percent of general practitioners to 46 percent of medical subspecialists. Only 19 percent, however, received income from prepaid sources, averaging $5,275 per physician. Reasons for joining or not joining are also examined. Participants joined most often to maintain or increase workload, while nonparticipants most often declined to join because they would be giving up independence.