Israel Medical Association Journal

Ubiquitin-proteasome degradation is a key cellular process involved in almost every aspect of cell life. According to the current concept, proteins are stable unless they are marked by poly-ubiquitination for degradation by the 26S proteasomes. A new twist in the concept became evident while studying the degradation of the tumor suppressor p53, a protein that appeared to satisfy this principle. We have discovered that native p53 is also prone to ubiquitin-independent 20S proteasomal degradation, suggesting that certain proteins are inherently unstable. We further found that this process of degradation is mediated by 20S proteasomes and inhibited by NADH quinone oxidoreductase 1. Our recent findings together with previous observations of ubiquitin-independent degradation suggest the existence of ubiquitin-independent mechanisms for proteasomal protein degradation in the cells.

Polyubiquitylation of cellular proteins has long been recognized as a prelude to a degradative fate in proteasomes. In recent years, however, ubiquitin conjugation has emerged as a regulatory strategy of considerable versatility. Most notably, monoubiquitylation is attributed an intimate role in trafficking of membrane proteins between various cellular compartments. Diverse classes of transmembrane proteins from across the eukaryotic spectrum (e.g., epidermal growth factor-receptor and other receptor tyrosine kinases) become modified with monoubiquitin molecules. Monoubiquitylation of substrates, in turn, regulates both their endocytosis at the plasma membrane and sorting in endosomes for delivery to lysosomes or vacuoles. A mechanistic rationale lies in the identification of a growing list of ubiquitin-binding domains carried by a variety of endocytic adaptor proteins. Thus, ubiquitin-conjugated membrane proteins may form extensive contacts with the endocytic machinery. Further, ubiquitin-binding adaptors and other endocytic components are, likewise, often monoubiquitylated. In this case, ubiquitin conjugation may serve to enhance intermolecular avidity in cargo-bound endocytic complexes, or alternatively, to mediate timely inactivation of ubiquitin-binding adaptors. Interestingly, the ubiquitin/endocytosis interface is appropriated by pathogenic organisms, for instance, during budding of viruses from host-infected cells. Moreover, compromised ubiquitin-mediated transport of certain signaling receptors is associated with disease states, including oncogenic transformation.

The Ink4a-Arf locus, which encodes two distinct tumor suppressor proteins, is inactivated in many cancers. Whereas p16^Ink4a is an inhibitor of cyclin D-dependent kinases, p19^Arf (p14^ARF in humans) antagonizes the E3 ubiquitin protein ligase activity of Mdm2 to activate p53. We now recognize that Arf functions in both p53-dependent and -independent modes to counteract hyper-proliferative signals originating from proto-oncogene activation, but its p53-independent activities remain poorly understood. Arf proteins are highly basic (> 20% arginine content, pI > 12) and predominantly localize within nucleoli in physical association with an abundant acidic protein, nucleophosmin (NPM/B23). When bound to NPM[1], Arf proteins are relatively stable with half-lives of 6–8 hours. Although mouse p19^Arf contains only a single lysine residue and human p14^ARF has none, both proteins are N-terminally ubiquitinated and degraded in proteasomes. Through as yet uncharacterized mechanisms, p19^Arf induces p53-independent sumoylation of a variety of cellular target proteins with which it interacts, including both Mdm2 and NPM. A naturally occurring NPM mutant (NPMc) expressed in myeloid leukemia cells redirects both wild-type NPM and p19^Arf to the cytoplasm, inhibits Arf-induced sumoylation, and attenuates p53 activity. Thus, ubiquitination and sumoylation can each influence Arf tumor suppressor activity.

Background: New drugs have significantly improved the prognosis and quality of life of patients with pulmonary arterial hypertension. However, PAH[1] associated with autoimmune disease, particularly progressive sclerosis, remains a very serious problem

Objectives: To evaluate whether the course of the disease and survival is significantly different in patients with PAH related to autoimmune disease as compared to other patients with PAH and to determine the prognostic factors in these patients.

Methods: We retrospectively compared 24 patients with PAH associated with autoimmune disease to 42 patients with other causes of PAH. We focused on the clinical and hemodynamic parameters and on the outcome.

Results: The early mortality rate was slightly higher in patients with PAH associated with autoimmune disease (13% after the first year, 25% after the fifth year). The prognostic factor was a shorter distance on the 6 minutes walking distance test (r = 0.2, P = 0.01).

Conclusions: The early detection of PAH associated with autoimmune disease should encourage earlier and more aggressive treatment than in idiopathic PAH.

Background: Anesthesiology is a vital specialty that permits the safe and humane performance of painful procedures. Most Israeli anesthesiologist are immigrants, while only a minimal number of Israeli medical school graduates enter the specialty. Unfortunately, the supply of immigrant physicians is declining due to falling immigration rates.

Objectives: To examine the current Israeli anesthesiology workforce and project future needs.

Methods: Demographic and professional information about Israeli hospital anesthesiologists was solicited from anesthesiology department heads. Data were also gathered about the past, present and projected future growth, age distribution and birth rate of the Israeli population. Needs and demand-based analyses were used to project future anesthesiology workforce requirements.

Results: Data about 711 anesthesiologists were obtained from 30 hospital anesthesiology department heads. Eighty-seven anesthesiologists (12.2%) graduated from Israeli medical schools and 459 (64.6%) graduated from medical schools in the former Soviet Union. Among the 154 anesthesiology residents were ≤ 40 years old, and only 13 (8.4%) graduated from Israeli medical schools There are approximately 10.8 anesthesiologists per 100,000 population. Projections for 2005–2015 revealed a need for 250–300 new anesthesiologists.
Conclusions: The anesthesiology workforce is predominantly composed of immigrants. This has vast implications for the future viability of the specialty because of the continuing reduction in immigration, the lack of interest in the specialty by Israeli medical school graduates, and the projected need for many new anesthesiologists to replace retirees and to provide care to a growing and aging population

Background: Debate continues in Israel as to whether to allow patients in public hospitals to choose their physician in return for an additional, out-of-pocket payment. One argument against this arrangement is that the most senior physicians will devote most of their time to private patients and not be sufficiently available to public patients with complex cases.

Objectives: To analyze the patterns of surgical seniority in Jerusalem hospitals from a number of perspectives, including the extent to which: a) opting for private care increases the likelihood of being treated by a very senior surgeon; b) public patients undergoing complex operations are being treated by very senior surgeons, c) the most senior surgeons allocate a significant portion of their time to private patients.

Methods: Demographic and clinical data were retrieved from the operating room records of three of the public hospitals in Jerusalem for all 38,840 operations performed in 2001. Of them, roughly 6000 operations (16%) were performed privately. Operations were classified as "most complex," "moderately complex" and "least complex" by averaging the independent ratings of eight medical and surgical experts. The surgeon's seniority was graded as "tenured" (tenured board-certified specialists, including department heads), "senior" (non-tenured board-certified specialists), and "residents." For each operation, we considered the seniority of the lead surgeon and of the most senior surgeon on the surgical team.

Results: The lead surgeon was of tenured rank in 99% of the most complex private cases and 74% of the most complex public cases, in 93% of the moderately complex private and 35% of the moderately complex public cases, and in 92% of the least complex private and 32% of the least complex public cases. The surgical team included a tenured physician in 97%, 66%, and 53% of the most complex, moderately complex, and least complex public operations, respectively. In both private and public cases, a board-certified (tenured or senior) specialist was a member of the surgical team for almost all of the most complex and moderately complex operations. On average, over half of the operations in which the lead surgeon was a department head were performed on public patients. Among tenured surgeons, those who spent more hours than their colleagues leading private operations also tended, on average, to spend more hours leading public operations.

Conclusions: Private patients have an advantage over public patients in terms of the seniority of the lead surgeon. However, there is also substantial involvement of very senior surgeons in the treatment of public patients, particularly in those cases that are most complex. 

Background: The contribution of the abnormal DNA mismatch repair system to non-small cell lung cancer tumorigenesis is controversial and has not been reported in Jewish Israeli patients. Similarly, the involvement of 3p deletions in NSCLC[1] in the same population has not been assessed.

Objectives: To assess the contribution of the DNA-MMR[2] system to NSCLC pathogenesis by analyzing microsatellite instability, and evaluate loss of heterozygosity at 3p rates in Israeli NSCLC patients.

Methods: Paired DNA from tumorous and non-tumorous tissue was extracted, and genotyping for MSI[3] determination was carried out using the five Bethesda markers and for determining LOH[4] two 3p markers were used. Genotyping was performed using polymerase chain reaction amplification and size separation on an ABI semiautomatic DNA sequencer, and the allelic patterns of tumorous and non-tumorous tissue were compared.

Results: Forty-four NSCLCs from 35 smokers and 9 non-smokers were analyzed, with 26 of the 44 (59%) at stage I disease. Using five microsatellite markers (D17S250, D5S346, D2S123, BAT-25, BAT-26) (known as Bethesda markers) for MSI determination, 6 of the 44 tumors (13.6%) exhibited MSI in at least one marker. Similarly, genotyping for LOH at chromosome 3p was performed using two markers (D3S4103, D3S1234) located at 3p14.2 l. With D3S4103, 33 of the 44 patients successfully analyzed were homozygous and therefore non-informative with respect to LOH. Using D3S1234, 33 of 36 patients (91.7%) were heterozygous, and 23 of these individuals' tumors (69.7%) displayed LOH. Unexpectedly, 4 of 33 tumors (12.1%) genotyped by D3S4103, and 16 of 36 tumors (44.5%) genotyped by D3S1234 showed a pattern of MSI, even though only one of these tumors showed a similar pattern when genotyped with the five consensus markers. Overall, 23 of 44 tumors (52.3%) demonstrated MSI on at least one marker, and 5 of these 23 tumors (21.7%) had MSI on two or more markers.

Conclusions: MSI using 3p markers and not the Bethesda markers occurs at a high rate and in early stages in Jewish NSCLC patients.

Background: Metastatic melanoma is an aggressive and highly malignant cancer. The 5 year survival rate of patients with metastatic disease is less than 5% with a median survival of only 6–10 months. Drugs like dacarbazin (DTIC) as a single agent or in combination with other chemotherapy agents have a response rate of 15–30%, but the duration of response is usually short with no impact on survival. Interleukin-2-based immunotherapy has shown more promising results. The National Institutes of Health recently reported that lymphodepleting chemotherapy, followed by an adoptive transfer of large numbers of anti-tumor specific tumor-infiltrating lymphocytes, resulted in an objective regression in 51% of patients.

Objectives: To introduce the TIL[1] technology to advanced metastatic melanoma patients in Israel.

Methods: We generated TIL cultures from tumor tissue, choosing those with specific activity against melanoma and expanding them to large numbers.

Results: TIL cultures from nine patients were established and examined for their specific activity against the patients' autologous tumor cells. Twelve TIL cultures derived from 5 different patients showed the desired anti-tumor activity, making those 5 patients potential candidates for the therapy.

Conclusions: Pre-clinical studies of the TIL technology in a clinical laboratory set-up were performed successfully and this modality is ready for treating metastatic melanoma patients at the Sheba Medical Center's Ella Institute.