Trends and Frequencies of Antibiotic Prescriptions for Acute Sinusitis Outpatient Visits in Adults

OBJECTIVE

The objective of this study was to analyze the trends and frequency in which recommended first-line therapy, amoxicillin with or without clavulanate, was prescribed for acute sinusitis based on current otolaryngology and other gold standard guidelines, as well as analyze differences in prescription behaviors of otolaryngologists compared with non-otolaryngologists for outpatient adult acute sinusitis visits.

METHODS

Weighted patient data from the National Ambulatory Medical Care Survey were analyzed to calculate visit rates and trends of antibiotic prescriptions for adults diagnosed with acute sinusitis from 2007 to 2019. Visits with multiple prescribed antibiotics or concomitant diagnoses requiring antibiotics were excluded. Each visit was classified based on the type of antibiotic prescribed.

RESULTS

Acute sinusitis was diagnosed in 0.63% of all outpatient visits from 2007 to 2019 (95% confidence interval: 0.56%-0.71%). Amoxicillin had the greatest increase in prescription frequency (13.4%), whereas macrolides had the largest decrease in prescription frequency (13.9%). Among adult acute sinusitis outpatient visits in which antibiotics were prescribed, recommended first-line antibiotic therapy of amoxicillin-clavulanate or amoxicillin alone was prescribed in 40.4% of visits. The most common antibiotic prescribed was amoxicillin-clavulanate at otolaryngologist visits (20.5%) and macrolides at non-otolaryngologist visits (26.0%). A greater proportion of otolaryngologist visits resulted in no antibiotics prescribed for acute sinusitis (36.8% vs. 22.5%, p < 0.001).

CONCLUSION

Otolaryngologists engage in watchful waiting more than non-otolaryngologists. Broader dissemination of existing guidelines for acute sinusitis treatment to non-Otolaryngologist (ENT) primary care specialties that take care of acute sinusitis to improve antibiotic stewardship and appropriate antibiotic selection is needed.

LEVEL OF EVIDENCE

4 Laryngoscope, 134:2622-2625, 2024.

Diffuse-Type Pancreatic Ductal Adenocarcinoma Mimicking Autoimmune Pancreatitis

Pancreatic ductal adenocarcinoma (PDAC) classically presents as a solitary mass on cross-sectional imaging. Diffuse-type PDAC is an unusual variant that accounts for 1%-5% of PDACs. Owing to its rarity, there are no established radiographic or endosonographic definitions. We report a unique case of diffuse-type PDAC presenting with imaging findings of 2 distinct masses in the pancreatic head and tail and with endoscopic ultrasound findings of diffuse gland enlargement mimicking autoimmune pancreatitis. The case illustrates the importance of sampling several areas of the pancreas when diffuse enlargement is present on endoscopic ultrasound and multiple masses are seen on cross-sectional imaging.

When to sweat: A history of chemotherapy in malignant sweat gland tumors. A unique case report and literature review

Sarcomatoid sweat gland carcinomas are rare among cutaneous cancers, with less than 20 cases described. A 54-year-old woman with sarcomatoid sweat gland carcinoma of the right upper extremity suffered extensive recurrence at 15 months, unresponsive to chemotherapy. There is no standard treatment or chemotherapy regimens for metastatic sweat gland carcinoma.

Sarcomatoid Eccrine Porocarcinoma in a Patient with Urothelial Carcinoma

Introduction/Objective

Sarcomatoid porocarcinoma of skin is an exceedingly rare and diagnostically challenging malignancy of the sweat gland. In this report, we describe a rare case of a sarcomatoid eccrine porocarcinoma initially diagnosed to be a squamous cell carcinoma (SCC) in a patient with metastatic urothelial carcinoma (UC).

Methods/Case Report

Our patient is a 60 year old male with stage IV, poorly differentiated UC status post TURBT with residual tumor, and a 4 x 3 x 1 cm, polypoid, ulcerating skin nodule on his right cheek presumptively diagnosed to be an SCC on biopsy at an outside hospital. Given the concern that this cutaneous lesion may be a metastatic UC with squamous differentiation, the skin nodule was re-biopsied at our hospital. On histology, the lesion consisted of sheets of squamoid, polygonal cells in the dermis with pleomorphic nuclei showing irregular contours, prominent nucleoli, coarse chromatin, and frequent mitoses. The tumor was focally connected to the epidermis, which established it as a primary skin neoplasm and not a metastatic lesion. The tumor cells stained diffusely positive for vimentin, AE1/AE3, CK5/6, HMW CK, CK7, p63, and p16, negative for CK20, GATA-3, BerEP4, and Sox10, and showed high Ki67 proliferation index. Within the tumor sheets were poorly formed, focal ductal elements that stained positive for CAM5.2, EMA, CEA, and CK19, and negative for p63. The tumor showed comedo necrosis, epidermal ulceration, and no keratinization. The tumor was diagnosed to be a porocarcinoma given its positive staining for CK7 and p16, presence of focal ductal elements, and epidermal connection, with sarcomatoid features indicated by strong vimentin expression.

Results (if a Case Study enter NA)

NA.

Conclusion

In this report, we described an exceedingly rare, diagnostically challenging case of a sarcomatoid porocarcinoma initially suspected to be a cutaneous SCC or metastatic UC with squamous differentiation. Although the tumor cells morphologically resembled SCC, its positive staining for CK7 and p16, presence of ductal elements, and lack of keratinization, favored a diagnosis of porocarcinoma rather than cutaneous SCC. Its focal connection to the epidermis and lack of GATA-3 expression favored a primary skin neoplasm rather than a metastatic UC. Its sarcomatoid nature was indicated by strong vimentin expression. Sarcomatoid porocarcinoma is diagnostically challenging given its rarity and potential to mimic other cutaneous malignancies such as SCC.

Metastasis of a Primary Sinonasal Alveolar Rhabdomyosarcoma to the Testicle in an Adult Patient

Introduction/Objective

Alveolar rhabdomyosarcoma is an aggressive tumor of skeletal muscle differentiation that predominantly affects adolescents and young adults, and is rare over 45 years of age. It has poor prognosis with metastasis, and most commonly spreads to the lymph nodes, bone marrow, and lungs. In this report, we describe a middle-aged patient with a primary sinonasal alveolar rhabdomyosarcoma which metastasized to the right testicle, an unusual metastatic site reported only a few times in literature.

Methods/Case Report

Our patient is a 53 year old male who presented in 2020 with recurrent epistaxis and bilateral cervical lymphadenopathy over a 2 month period. Maxillofacial CT/MRI imaging revealed a 4-cm sized mass within the left nasal cavity eroding into the ethmoid sinuses. The patient underwent endoscopic sinus surgery of the sinonasal mass, which on histology, appeared as poorly differentiated small round blue cells with numerous mitoses infiltrating as single cells and nests. These cells stained positive for vimentin, myogenin, desmin, and CD56, and negative for AE1/AE3, chromogranin, S-100, CD99, and CD45. The cells showed very high Ki67 proliferation index (70-80%) and tested positive for FOXO1 gene rearrangement, which supported the diagnosis of alveolar rhabdomyosarcoma. The patient completed chemoradiation therapy, and MRI scans over the next 2 years were negative for residual sinonasal tumor. However, the patient returned in 2022 after having undergone a right orchiectomy at an outside hospital for testicular pain, and abdominal CT showed diffuse retroperitoneal lymphadenopathy concerning for metastasis. On histology, the resected testicle showed seminiferous tubules infiltrated and destroyed by sheets of poorly differentiated small round blue cells with fibrous septae separating the nests of tumor cells into alveolar-like spaces with central loss of cohesion. The tumor cells showed the same immunohistochemical staining pattern as the primary sinonasal lesion, thus confirming it to be metastatic alveolar rhabdomyosarcoma.

Results (if a Case Study enter NA)

NA.

Conclusion

It is unusual for alveolar rhabdomyosarcomas to occur in adults over 45 years old, and is even rarer for these tumors to metastasize to the testicle. Metastases also only account for 1% of testicular tumors. Our report documents a very rare case of an alveolar rhabdomyosarcoma in a middle-aged adult which metastasized to the testicle after chemoradiation therapy.

Two Cases of Duodenal Neuroendocrine (Carcinoid) Tumor Concurrent with Invasive Gastric Adenocarcinoma and Pancreatic Intraductal Papillary Mucinous Neoplasm

Introduction/Objective

Neuroendocrine (carcinoid) tumors of the duodenum are extremely rare and account for only 2-4% of gastrointestinal tract neuroendocrine tumors. We report two cases of incidentally discovered duodenal neuroendocrine tumor which respectively occurred in a patient with invasive gastric adenocarcinoma and in a patient with pancreatic intraductal papillary mucinous neoplasm (IPMN).

Methods/Case Report

The first case involved a 60-year old male who presented with melena and symptomatic anemia and was found on EGD to have a large circumferential mass at the gastric antrum/pylorus, which was revealed to be an invasive gastric adenocarcinoma on biopsy. At the time of distal gastrectomy for this malignancy, a concurrent, 0.6 cm-sized, low grade neuroendocrine tumor was incidentally discovered at the duodenal margin. The duodenal tumor consisted of nests and trabeculae of monotonous cells with ovoid/round nuclei, finely speckled “salt and pepper” chromatin, and low mitotic rate (&lt; 2 mitoses/2 mm2), and invaded only into submucosa. The tumor cells were strongly and diffusely positive for neuroendocrine markers chromogranin, synaptophysin, and CD56, positive for CK7 and CDX2, negative for CK20, and with low Ki67 proliferation index (&lt; 3%). The second case involved a 69-year old female who presented with epigastric pain and was found on abdominal CT to have a 4 cm-sized cystic mass in the pancreatic head. While biopsy of the pancreatic mass revealed an IPMN, a separate biopsy of an incidentally discovered, 1 cm-deep ulcer in the duodenum bulb revealed a low-grade neuroendocrine tumor with similar morphologic features, mitotic rate, and immunohistochemical staining pattern as the prior case while also negative for IMP3 stain. The patient had normal serum gastrin and urine HIAA levels, but elevated serum chromogranin-A levels.

Results (if a Case Study enter NA)

NA.

Conclusion

Duodenal carcinoids are rare (1-3% of primary duodenal tumors) and are mostly non-functional and unifocal. The duodenum is also the least common site (2-4%) for GI tract neuroendocrine tumors. The pathophysiology of these tumors is still poorly understood, with the majority occurring sporadically and a minority in the setting of hereditary cancer syndromes. This report documents two very rare instances of duodenal neuroendocrine tumor incidentally discovered with invasive gastric adenocarcinoma and pancreatic IPMN.

Depressive symptoms are associated with immunological failure among HIV-positive patients in Vietnam

As the lives of people living with HIV (PLWH) become increasingly normalized, more focus is being given to the associated comorbidities of HIV, including those related to mental health such as depression. This study aims to evaluate the correlation between depressive symptoms and HIV outcomes in Vietnam through the measurement of CD4 cell count. A mixed design was utilized, in which both a longitudinal assessment of CD4 cell counts and a cross-sectional survey of depressive symptoms were conducted on 481 patients in the Bach Mai and Ha Dong HIV clinics (Hanoi, Vietnam). CD4 cell count data was extracted from the medical records of participants, and depressive symptoms were screened using the Patient Health Questionnaire (PHQ-9). The results illustrate that the presence of moderately severe to severe depressive symptoms is associated with lower CD4 cell counts, indicating poorer HIV outcomes resulting from comorbid depression. This correlation was especially noticeable in the PHQ-9 items for psychomotor agitation/retardation (p < 0.05) and suicidal ideation (p < 0.05). Future policy and treatment options for HIV in Vietnam should consider the presence of comorbid mental health conditions in order to provide more suitable and effective treatment in the goal of providing a higher quality of life for PLWH.

Cannabis Abuse and Perioperative Complications After Treatment of Intracranial Aneurysms: A Nationwide Analysis

OBJECTIVE

In the present retrospective cohort analysis, we examined the differences in baseline characteristics and peri- and postoperative outcomes stratified by 3 groups: cannabis abuse or dependence versus none, surgical versus endovascular treatment, and unruptured and ruptured intracranial aneurysms.

METHODS

A study population of 26,868 patients was defined using the 2009-2016 National Inpatient Sample database. The baseline characteristics were compared between the cannabis and no-cannabis groups, and the traits that differed significantly were factored into the multivariate analysis using 1:1 propensity score matching. The matched groups were analyzed to compare the cannabis and no-cannabis cohorts for the following endpoints: mortality, length of stay, discharge disposition, total hospital charges, and several peri- and postoperative outcomes.

RESULTS

In the surgically and endovascularly treated groups for unruptured intracranial aneurysms, those in the cannabis group were more likely to be male and younger and to smoke tobacco than were those in the no-cannabis group. After matching, no significant endpoint differences were noted. Similarly, in the surgically and endovascularly treated ruptured aneurysm groups, those in the cannabis group were more likely to be male and younger and to smoke tobacco. After matching, the cannabis group within the endovascular treatment group had had a longer length of stay and were more likely to have developed any hydrocephalus, obstructive hydrocephalus, sepsis, and acute kidney injury. Those in the cannabis group who had undergone surgery were more likely to have developed any hydrocephalus, specifically, communicating hydrocephalus.

CONCLUSIONS

The cannabis group with ruptured intracranial aneurysms was more likely to experience certain adverse outcomes after surgical or endovascular treatment compared with the no-cannabis group. However, such was not the case for cannabis abusers treated for unruptured aneurysms.

Biphasic Sarcomatoid Sweat Gland Carcinoma With Ductal Epithelial And Spindled Myoepithelial Cell Components (Malignant Mixed Tumor Of Skin)

Introduction/Objective

Sweat gland carcinomas are a group of malignant skin adnexal tumors that are difficult to diagnose due to their rarity, wide morphologic variation, and limited literature on diagnosis and classification. These tumors may appear bland and morphologically resemble benign skin adnexal tumors, or may appear poorly differentiated and mimic metastatic carcinoma especially from a breast primary. Biphasic sweat gland carcinomas are an even rarer entity, with only few cases reported in literature, and have been described to consist of a well- differentiated ductal epithelial component and a poorly differentiated, sarcomatoid, spindle cell component.

Methods/Case Report

Our case report describes a 53 year old female referred to our institution for diagnosis of an excised skin lesion of the right upper arm, which had been slowly growing for 8 years. The histology revealed a biphasic malignant neoplasm involving the dermis and subcutis. The tumor consisted of an epithelial cell component with glandular and squamoid morphology and positive for CK5/6, CK7, and CAM5.2, and a spindled myoepithelial cell component with sarcomatoid morphology and positive for S100, vimentin, and p63. Stains for CK20, ER, PR, PAX8, CEA, and TTF1 were negative. The histological and clinical findings favored a primary skin adnexal tumor, rather than a metastatic lesion.

The patient underwent wide local excision of the lesion given that margins of the original excision were indeterminate. The histology of this re-excision demonstrated the same biphasic tumor with ductal epithelial and sarcomatoid myoepithelial cell components positive for the same stains. Although margins were negative in this re-excision, 3-4 months later, the patient developed dyspnea with multiple new pulmonary and hilar masses discovered on imaging, and new-onset headache with a frontal lobe mass discovered on brain imaging. These masses were biopsied/resected, and revealed to be metastases of the original cutaneous tumor positive for the same markers.

Results (if a Case Study enter NA)

NA

Conclusion

This case report describes a rare, diagnostically challenging case of a biphasic sweat gland carcinoma with ductal epithelial and sarcomatoid myoepithelial cell components, which demonstrated aggressive behavior with distant metastasis. These tumors are a clinicopathological quandary given their rarity and the paucity of literature on their characterization.

Distribution of Paycheck Protection Program to otolaryngology practices during the COVID-19 pandemic

BACKGROUND

The Coronavirus disease of 2019 (COVID-19) has impacted physician practices in many ways with some ENT clinics reporting around a 50% drop in completed scheduled ENT visits during the first wave of the pandemic compared to 2019.

AIMS

This study surveyed first round PPP loan disbursement to otolaryngology practices in the United States in response to COVID-19.

METHODS

A cross-sectional study was conducted using publicly available data published on PPP by the SBA. Otolaryngology clinics receiving loans greater than $0.15M were filtered using the following terms: "otolaryngology", "otolaryngologist","sinus", "head and neck", "throat", "ENT", and "facial plastic". 481 ENT clinics that received loans greater than $0.15 M from the Paycheck Protection Program (PPP) were identified. Loan amount, business type, geographicregion, owner race, owner gender, and the number of jobs per business were recorded for each clinic. Chi-square analysis was performed to determine significance (P < 0.05) of each characteristic.

RESULTS

Loan distribution was significantly different based on jobs reported (P < .001) and business type (P < .001). 100% of loans ranging from $0.15 M to $0.35 M went to micro and small practices whereas 33% of medium-sized practices received loans greater than $1 M. Higher proportions of Subchapter corporations (60.00%) received smaller loans of $0.15 to $0.35 M than Limited Liability Companies (39.13%) and Corporations (51.69%) which generally employ more people.

DISCUSSION

Loan distribution was significantly different between businesses based on jobs reported (P < 0.001), with micro/small practices recieving smaller loans than their medium counterparts. All large businesses recived loans in in excess of $2 M. This suggests proportional distribution of loans in accordance with jobs reported.

CONCLUSION

This study suggests PPP funding was objectively distributed to ENT clinics based on staff size.

LEVEL OF EVIDENCE

Level 4.

Suppression of Nestin reveals a critical role for p38-EGFR pathway in neural progenitor cell proliferation

The expression of intermediate filament Nestin is necessary for the neural progenitor cells (NPCs) to maintain stemness, but the underlying cellular and molecular mechanism remains unclear. In this study, we demonstrated that Nestin is required for the self-renew of NPCs through activating MAPK and EGFR pathways. Knockdown of Nestin by shRNA inhibited cell cycle progression and proliferation in mouse NPCs. Moreover, suppression of Nestin reduced expression of the epidermal growth factor receptor (EGFR) in NPCs and inhibited the mitogenic effects of EGF on these cells. Treatment of NPCs with p38-MAPK inhibitor PD169316 reversed cell cycle arrest caused by the knockdown of Nestin. Our findings indicate that Nestin promotes NPC proliferation via p38-MAPK and EGFR pathways, and reveals the necessity of these pathways in NPCs self-renewal.

Osciladores Caóticos implementados en Microcontrolador PIC18F

Introducción: Recientemente, los sistemas caóticos han llamado la atención de la comunidad científica internacional, debido a sus potenciales aplicaciones en varias ramas de la ciencia e ingeniería. Se han propuesto muchos trabajos con el fin de resolver algunos problemas interesantes, como la determinación de daños estructurales en los materiales o en sistemas de comunicaciones seguras. Sin embargo, la mayoría de estos trabajos se enfocan en sistemas caóticos en tiempo continuo, mientras que en muchos casos, es deseable que estos sistemas estén en el modo de tiempo discreto y puedan ser utilizados en tiempo real.                      Método: El presente trabajo propone la implementación experimental de tres osciladores caóticos discretizados en un microcontrolador simple. Los osciladores caóticos a implementar son muy conocidos y muy utilizados para ejemplificar posibles soluciones a diversos problemas: los osciladores de Lorenz, Rössler y Chen. Para lo cual, se utilizan tan solo un microcontrolador de bajo costo, unos cuantos resistores y un algoritmo de computación sencillo.Resultados: Se obtiene un sistema embebido de bajo costo y sencillo para implementar osciladores caóticos discretizados.                     Discusión o Conclusión: Se demuestra que los osciladores caóticos de Lorenz, Rössler y Chen pueden implementarse en cualquier microcontrolador de arquitectura basada en palabras de 18 bits o más. Además, se observa que el algoritmo propuesto se pude migrar de un oscilador a otro con solo sustituir el sistema caótico de ecuaciones.

Identification and analysis of murine pancreatic islet enhancers

AIMS/HYPOTHESIS

The paucity of information on the epigenetic barriers that are blocking reprogramming protocols, and on what makes a beta cell unique, has hampered efforts to develop novel beta cell sources. Here, we aimed to identify enhancers in pancreatic islets, to understand their developmental ontologies, and to identify enhancers unique to islets to increase our understanding of islet-specific gene expression.

METHODS

We combined H3K4me1-based nucleosome predictions with pancreatic and duodenal homeobox 1 (PDX1), neurogenic differentiation 1 (NEUROD1), v-Maf musculoaponeurotic fibrosarcoma oncogene family, protein A (MAFA) and forkhead box A2 (FOXA2) occupancy data to identify enhancers in mouse islets.

RESULTS

We identified 22,223 putative enhancer loci in in vivo mouse islets. Our validation experiments suggest that nearly half of these loci are active in regulating islet gene expression, with the remaining regions probably poised for activity. We showed that these loci have at least nine developmental ontologies, and that islet enhancers predominately acquire H3K4me1 during differentiation. We next discriminated 1,799 enhancers unique to islets and showed that these islet-specific enhancers have reduced association with annotated genes, and identified a subset that are instead associated with novel islet-specific long non-coding RNAs (lncRNAs).

CONCLUSIONS/INTERPRETATIONS

Our results indicate that genes with islet-specific expression and function tend to have enhancers devoid of histone methylation marks or, less often, that are bivalent or repressed, in embryonic stem cells and liver. Further, we identify a subset of enhancers unique to islets that are associated with novel islet-specific genes and lncRNAs. We anticipate that these data will facilitate the development of novel sources of functional beta cell mass.

Ba2YCu3O6.9 Powder Preparation by Sol-Gel Emulsion Techniques

Barium yttrium cuprate powders were prepared by a sol-gel emulsion process in which an aqueous nitrate solution containing Ba, Y, and Cu in the correct stoichiometry was emulsified in heptane. The resulting micrometer-sized droplets were gelled by adding a high-molecular-weight primary amine that extracts nitric acid from the aqueous phase and raises the pH of the droplets. Thermal gravimetric analysis revealed that the correct overall stoichiometry was obtained at temperatures lower than 400 °C during calcination, but X-ray diffraction showed that calcination at temperatures greater than 800° may be required to produce the correct phase. One possible advantage of this technique is the control of powder morphology on a micrometer scale so that powders can be prepared for advanced ceramics processing methods. Also, segregation of components, if any, will be restricted to distances less than one micrometer.

OP-1 (BMP-7) stimulates osteoprogenitor cell differentiation in the presence of polymethylmethacrylate particles

Polymethylmethacrylate (PMMA) particles have been shown to inhibit the differentiation, proliferation, and mineralization of osteoprogenitor cells in vitro. In this study, we investigated the effects of OP-1 (BMP-7) on the osteogenesis of MC3T3-E1 osteoprogenitor cells exposed to PMMA particles in vitro. MC3T3-E1 cells challenged with PMMA particles on the 1st day of differentiation in osteogenic culture showed a significant dose-dependent decrease in mineralization and alkaline phosphatase expression over a 20-day culture period. Exposure of these cells to OP-1 (200 ng/mL) during days 1-4, 1-20, and 4-20 in the presence of PMMA particles resulted in significant increases in mineralization and alkaline phosphatase expression at all particle doses. Addition of OP-1 to MC3T3-E1 cultures challenged with PMMA particles on the 4th day of differentiation in osteogenic media also resulted in significant increases in mineralization and alkaline phosphatase expression. This study has shown that OP-1 stimulates osteogenesis in MC3T3-E1 osteoprogenitor cells that have been inhibited by PMMA particles. Local administration of OP-1 to the site of osteolysis may be a potential adjunctive therapy to reverse the bone destruction due to wear particles.

Curettage and cryosurgery for low-grade cartilage tumors is associated with low recurrence and high function

BACKGROUND

Chondrosarcomas of bone traditionally have been treated by wide or radical excision, procedures that may result in considerable lifelong disability. Grade 1 chondrosarcomas have little or no metastatic potential and are often difficult to distinguish from painful benign enchondromas. Curettage with adjuvant cryosurgery has been proposed as an alternative therapy for Grade 1 chondrosarcomas given the generally better function after the procedure. However, because it is an intralesional procedure, curettage and cryosurgery may be associated with higher rates of recurrence.

QUESTIONS/PURPOSES

We asked whether Grade 1 chondrosarcomas and enchondromas of uncertain malignant potential treated by curettage and cryosurgery are associated with low recurrence rates and high functional scores.

PATIENTS AND METHODS

We retrospectively reviewed the records of 46 patients with Grade 1 chondrosarcomas and enchondromas of uncertain malignant potential treated by curettage and cryosurgery. Forty-one patients had tumors of the long bones. Patients were followed a minimum of 18 months (average, 47.2. months; range, 18-134 months) for evidence of recurrence and for assessment of Musculoskeletal Tumor Society (MSTS) functional score.

RESULTS

Two of the 46 patients had recurrences in the original tumor site (4.3% recurrence rate), which subsequently were removed by wide excision, and both patients were confirmed to be disease-free 36 and 30 months, respectively, after the second surgery. The mean MSTS score was 27.2 of 30 points (median, 29 points).

CONCLUSIONS

Our observations show curettage with cryosurgery is associated with low recurrence of Grade 1 chondrosarcoma and high functional scores. Curettage with cryosurgery is a reasonable alternative to wide or radical excision as the treatment for Grade 1 chondrosarcomas, and allows for more radical surgery in the event of local recurrence.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Polymethylmethacrylate particle exposure causes changes in p38 MAPK and TGF-beta signaling in differentiating MC3T3-E1 cells

Periprosthetic osteolysis of joint replacements caused by wear debris is a significant complication of joint replacements. Polymethylmethacrylate (PMMA) particles have been shown to inhibit osteogenic differentiation, but the molecular mechanism has not been previously determined. In this study, we exposed differentiating MC3T3-E1 preostoblast cells to PMMA particles and determined the changes that occurred with respect to p38 mitogen-activated protein kinase (MAPK) activity and the transforming growth factor (TGF)-beta1 and bone morphogenetic protein (BMP) signaling pathways. In the absence of particles, MC3T3-E1 cells demonstrate activation of p38 MAPK on day 8 of differentiation; however, when treated with PMMA particles, differentiating MC3T3-E1 cells demonstrate the suppression of p38 activity on day 8 and show activation of p38 on days 1 and 4. On day 4 of particle exposure, the differentiating MC3T3-E1 cells show significant downregulation of TGF-beta1 expression, which is involved in osteoblast differentiation, and a significant upregulation of the expression of BMP3 and Sclerostin (SOST), which are negative regulators of osteoblast differentiation. By day 8 of particle exposure, the changes in TGF-beta1, BMP3, and SOST expression are opposite of those seen on day 4. This study has demonstrated the distinct changes in the molecular profile of MC3T3-E1 cells during particle-induced inhibition of osteoblast differentiation. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010.

Polymethylmethacrylate particles impair osteoprogenitor viability and expression of osteogenic transcription factors Runx2, osterix, and Dlx5

Polymethylmethacrylate (PMMA) particles have been shown to inhibit the differentiation of osteoprogenitor cells, but the mechanism of this inhibitory effect has not been investigated. We hypothesize that the inhibitory effects of PMMA particles involve impairment of osteoprogenitor viability and direct inhibition of transcription factors that regulate osteogenesis. We challenged MC3T3-E1 osteoprogenitors with PMMA particles and examined the effects of these materials on osteoprogenitor viability and expression of transcription factors Runx2, osterix, Dlx5, and Msx2. MC3T3-E1 cells treated with PMMA particles over a 72-h period showed a significant reduction in cell viability and proliferation as indicated by a dose- and time-dependent increase in supernatant levels of lactate dehydrogenase, an intracellular enzyme released from dead cells, a dose-dependent decrease in cell number and BrdU uptake, and the presence of large numbers of positively labeled Annexin V-stained cells. The absence of apoptotic cells on TUNEL assay indicated that cell death occurred by necrosis, not apoptosis. MC3T3-E1 cells challenged with PMMA particles during the first 6 days of differentiation in osteogenic medium showed a significant dose-dependent decrease in the RNA expression of Runx2, osterix, and Dlx5 on all days of measurement, while the RNA expression of Msx2, an antagonist of Dlx5-induced osteogenesis, remained relatively unaffected. These results indicate that PMMA particles impair osteoprogenitor viability and inhibit the expression of transcription factors that promote osteoprogenitor differentiation.

Ultrahigh molecular weight polyethylene wear debris inhibits osteoprogenitor proliferation and differentiation in vitro

Polyethylene wear debris induces progressive osteolysis by increasing bone degradation and suppressing bone formation. Polyethylene particles inhibit the function of mature osteoblasts, but whether polyethylene particles also interfere with the proliferation and differentiation of osteoprogenitor cells is unknown. In this study, we investigated the effects of ultrahigh molecular weight polyethylene (UHMWPE) particles on the osteogenic activity of primary murine bone marrow osteoprogenitors and MC3T3-E1 preosteoblastic cells in vitro. Submicron-sized UHMWPE particles generated from wear simulator tests were isolated from serum-containing solution by density gradient centrifugation. The particles were coated onto the surface of culture wells at concentrations of 0.038, 0.075, 0.150, 0.300, and 0.600% v/v in a layer of type I collagen matrix. Primary murine bone marrow cells and MC3T3-E1 preosteoblasts were seeded onto the particle-collagen matrix and induced to differentiate in osteogenic medium for 20 days. Exposure of both cell populations to UHMWPE particles resulted in a dose-dependent decrease in mineralization, proliferation, alkaline phosphatase activity, and osteocalcin production when compared with control cells cultured on collagen matrix without particles. Complete suppression of osteogenesis was observed at particle concentrations > or =0.150% v/v. This study demonstrated that UHMWPE particles inhibit the osteogenic activity of osteoprogenitor cells, which may result in reduced periprosthetic bone regeneration and repair.

Polymethylmethacrylate particles inhibit osteoblastic differentiation of MC3T3-E1 osteoprogenitor cells

Orthopedic wear debris has been implicated as a significant inhibitory factor of osteoblast differentiation. Polymethylmethacrylate (PMMA) particles have been previously shown to inhibit the differentiation of osteoprogenitors in heterogeneous murine marrow stromal cell cultures, but the effect of PMMA particles on pure osteoprogenitor populations remains unknown. In this study, we challenged murine MC3T3-E1 osteoprogenitor cells with PMMA particles during their initial differentiation in osteogenic medium. MC3T3-E1 cultures challenged with PMMA particles showed a gradual dose-dependent decrease in mineralization, cell number, and alkaline phosphatase activity at low particle doses (0.038-0.150% v/v) and complete reduction of these outcome parameters at high particle doses (> or =0.300% v/v). MC3T3-E1 cultures challenged with a high particle dose (0.300% v/v) showed no rise in these outcome parameters over time, whereas cultures challenged with a low particle dose (0.075% v/v) showed a normal or reduced rate of increase compared to controls. Osteocalcin production was not significantly affected by particles at all doses tested. MC3T3-E1 cells grown in conditioned medium from particle-treated MC3T3-E1 cultures showed a significant reduction in mineralization only. These results indicate that direct exposure of MC3T3-E1 osteoprogenitors to PMMA particles results in suppression of osteogenic proliferation and differentiation.

Polymethylmethacrylate particles inhibit osteoblastic differentiation of bone marrow osteoprogenitor cells

Aseptic implant loosening of total joint replacements often results from particle-mediated bone loss, which may be a combined effect of osteolysis and suppressed bone formation. Bone regeneration in the prosthetic bed depends on the activity of osteoblasts and their differentiation from osteoprogenitors in the bone marrow. This study investigated the effects of polymethylmethacrylate (PMMA) particles on the ability of bone marrow osteoprogenitors to differentiate into osteoblasts in vitro. Murine bone marrow cells challenged with PMMA particles on the first day of differentiation in osteogenic medium showed a dose-dependent decrease in osteoprogenitor proliferation, alkaline phosphatase expression, and mineralization. Undifferentiated bone marrow cells pretreated with PMMA particles in nonosteogenic medium for 5 days also showed a dose-dependent loss in osteogenic potential, which was sustained throughout subsequent growth in particle-free, osteogenic medium. Bone marrow cells challenged with PMMA particles after the fifth day of differentiation in osteogenic medium showed significant reductions in cellular proliferation, but not alkaline phosphatase expression and mineralization, indicating that bone marrow cells were most sensitive to particle treatment during the first 5 days of differentiation. This study demonstrated that PMMA particles inhibit osteoblastic differentiation of bone marrow osteoprogenitor cells, which may contribute to periprosthetic bone loss and implant failure.

Effects of a p38 MAP kinase inhibitor on bone ingrowth and tissue differentiation in rabbit chambers

The effects of an oral p38 mitogen-activated protein kinase (MAPK) inhibitor and polyethylene particles separately and together on tissue differentiation in the bone harvest chamber (BHC) in rabbits over a 3-week treatment period were investigated. The harvested tissue was analyzed histomorphometrically for markers of bone formation (percentage of bone area), osteoblasts (alkaline phosphatase staining), and osteoclasts (CD51, the alpha chain of the vitronectin receptor). Polyethylene particles decreased the percentage of bone ingrowth and staining for alkaline phosphatase. The p38 MAPK inhibitor alone decreased alkaline phosphatase staining. When the oral p38 MAPK inhibitor was given and the chamber contained polyethylene particles, there was a suppression of bone ingrowth and alkaline phosphatase staining. In contrast to oral non-steroidal anti-inflammatory drugs (NSAIDs) and local Interleukin-1 receptor antagonist (IL-1ra) administration, the oral p38 MAPK inhibitor alone did not suppress bone formation when given during the initial phase of tissue differentiation. Particle-induced inflammation and the foreign body reaction were not curtailed when the p38 MAPK inhibitor was given simultaneously with particles. Additional experiments are needed to establish the efficacy of p38 MAPK inhibitor administration on mitigating an established inflammatory and foreign body reaction that parallels the clinical situation more closely.

Kinetics of polymethylmethacrylate particle-induced inhibition of osteoprogenitor differentiation and proliferation

Periprosthetic bone loss induced by implant wear debris may be a combined effect of osteolysis and reduced bone formation resulting from particle-induced suppression of osteoprogenitor differentiation. This study investigated the time-dependent effects of polymethylmethacrylate (PMMA) particles on the osteogenic capability of bone marrow osteoprogenitor cells during the early phase of differentiation. Murine bone marrow cells were challenged with PMMA particles (0.30% v/v) on the first day of growth in osteogenic medium. Particles were removed from culture after 1, 3, and 5 days, respectively, after which cell growth in osteogenic medium was continued until the 15th day. Bone marrow osteoprogenitor cells exposed to particles during the first 5 days of differentiation showed complete, irreversible inhibition of proliferation, alkaline phosphatase expression, and mineralization. Osteoprogenitors exposed to particles for more than 5 days showed the same degree of inhibition, while those exposed to particles for less than 5 days showed a diminished inhibitory response. Conditioned medium from particle-treated cells did not suppress osteogenic development, demonstrating that suppression of osteogenesis was not due to secreted inhibitory factors. This study has shown that the early phase of osteoprogenitor differentiation is a crucial time period during which exposure to PMMA particles causes irreversible inhibition of osteogenesis.

Effects of orthopaedic wear particles on osteoprogenitor cells

Wear particles from total joint arthroplasties are constantly being generated throughout the lifetime of an implant. Since mesenchymal stem cells and osteoprogenitors from the bone marrow are the precursors of osteoblasts, the reaction of these cells to orthopaedic wear particles is critical to both initial osseointegration of implants and ongoing regeneration of the periprosthetic bed. Particles less than 5 microm can undergo phagocytosis by mature osteoblasts, with potential adverse effects on cellular viability, proliferation and function. The specific effects are dependent on particle composition and dose. Metal and polymer particles in non-toxic doses stimulate pro-inflammatory factor release more than ceramic particles of a similar size. The released factors inhibit markers of bone formation and are capable of stimulating osteoclast-mediated bone resorption. Mesenchymal stem cells and osteoprogenitors are also profoundly affected by wear particles. Titanium and polymethylmethacrylate particles inhibit bone cell viability and proliferation, and downregulate markers of bone formation in a dose- and time-dependent manner. Future studies should delineate the molecular mechanisms by which particles adversely affect mesenchymal stems cells and the bone cell lineage and provide strategies to modulate these effects.

Conformational States of Cytochrome P450cam Revealed by Trapping of Synthetic Molecular Wires

Members of the ubiquitous cytochrome P450 family catalyze a vast range of biologically significant reactions in mammals, plants, fungi, and bacteria. Some P450s display a remarkable promiscuity in substrate recognition, while others are very specific with respect to substrate binding or regio and stereo-selective catalysis. Recent results have suggested that conformational flexibility in the substrate access channel of many P450s may play an important role in controlling these effects. Here, we report the X-ray crystal structures at 1.8A and 1.5A of cytochrome P450cam complexed with two synthetic molecular wires, D-4-Ad and D-8-Ad, consisting of a dansyl fluorophore linked to an adamantyl substrate analog via an alpha,omega-diaminoalkane chain of varying length. Both wires bind with the adamantyl moiety in similar positions at the camphor-binding site. However, each wire induces a distinct conformational response in the protein that differs from the camphor-bound structure. The changes involve significant movements of the F, G, and I helices, allowing the substrate access channel to adapt to the variable length of the probe. Wire-induced opening of the substrate channel also alters the I helix bulge and Thr252 at the active site with binding of water that has been proposed to assist in peroxy bond cleavage. The structures suggest that the coupling of substrate-induced conformational changes to active-site residues may be different in P450cam and recently described mammalian P450 structures. The wire-induced changes may be representative of the conformational intermediates that must exist transiently during substrate entry and product egress, providing a view of how substrates enter the deeply buried active site. They also support observed examples of conformational plasticity that are believed be responsible for the promiscuity of drug metabolizing P450s. Observation of such large changes in P450cam suggests that substrate channel plasticity is a general property inherent to all P450 structures.

Renin-angiotensin system blockade in biopsy-proven allograft nephropathy

Allograft nephropathy leads to progressive renal injury and ultimate graft loss. In native kidney disease, the use of angiotensin-converting enzyme inhibitors (ACEi) or angiotensin receptor blockers (ARB) is beneficial in retarding the decline of renal function. We reviewed a cohort of renal transplant recipients who were prescribed either an ACEi or ARB for biopsy-proven allograft nephropathy. Patients were followed from time of initiation of ACEi/ARB and were stratified based on biopsy findings. Outcomes of interest included safety, allograft survival, renal function, and rate of renal function decline pre- and post-ACEi/ARB. The 5-year allograft survival after biopsy was 83%. Mean serum creatinine was 2.2 +/- 1.1 mg/dL (range 1.0 to 4.3) at time of biopsy and 2.6 +/- 1.2 mg/dL (1.2 to 6.5) at last follow-up. The mean slope of the creatinine versus time (SD) was 2.43 (7.93) in the 12 months prior to therapy and 1.45 (3.66) following therapy, with the absolute difference in slope -3.38 (6.06) (P =.0004). We conclude that treatment with ACEi/ARB is beneficial in the management of allograft nephropathy.

Regulation of the Expression of the Prostate-specific Antigen by Claudin-7

Claudins are a family of proteins involved in forming tight junctions between cells. Here we describe two forms of claudin-7 (CLDN-7), a full-length form of CLDN-7 with 211 amino-acid residues and a C-terminal truncated form with 158 amino-acid residues. These two forms of CLDN-7 are able to regulate the expression of a tissue-specific protein, the prostate-specific antigen (PSA), in the LNCaP prostate cancer cell line. We also found that the expression of CLDN-7 is responsive to androgen stimulation in the LNCaP cell line, suggesting that this protein is involved in the regulatory mechanism of androgen. Both forms of claudin-7 are expressed in human prostate, kidney and lung samples, and in most samples, the full-length form of claudin-7 was predominant. However, in some prostate samples from healthy individuals, the truncated form of claudin-7 is predominantly expressed. Our results demonstrated that unlike other claudins, CLDN-7 has both structural and regulatory functions, and the two forms of CLDN-7 may be related to cell differentiation in organ development.

Autologous chondrocyte implantation

Rationale for the treatment of cartilage damage in younger patients depends on a thorough understanding of the predisposing factors for the chondrosis and the stage of disease. Implantation with autologous cultured chondrocytes allows for resurfacing of larger defect areas with reproducibly good/excellent results in 90% of patients with isolated lesions of the femoral condyle. Patellar lesions also may be successfully treated (approximately 75% improved) but strict attention must be given to correction of malalignment. Results in patients with tibial and salvage lesions are encouraging; however, these results should be viewed with caution due to the small number of patients with 2-year follow-up. Autologous chondrocyte implantation involves an open technique with the inherent disadvantages of adhesions and a more prolonged recovery. However, these disadvantages must be weighed against the procedure's ability to produce a hyaline-type tissue with greater durability than fibrocartilage repairs produced by traditional marrow-stimulation techniques. We recommended matching the treatment procedure to patient expectations and lesion/demographic characteristics. Based on the available literature. algorithms have been published that recommend autologous chondrocyte implantation be reserved as first-line treatment for high-demand patients with large lesions (>2 cm2) and as revision therapy in patients with lesions of all sizes, regardless of patient demand, who have failed alternative marrow stimulation techniques.

Fluorescent probes for cytochrome p450 structural characterization and inhibitor screening

We have synthesized two luminescent probes (D-4-Ad and D-8-Ad) that target cytochrome P450cam. D-4-Ad luminescence is quenched by Förster energy transfer upon binding (Kd = 0.83 muM) but is restored when the probe is displaced from the active site by camphor. In contrast, D-8-Ad (Kd approximately 0.02 muM) is not displaced from the enzyme, even in the presence of a large excess of camphor. The 2.2 A resolution crystal structure of the D-8-Ad:P450cam complex reveals extensive hydrophobic contacts between the probe and the enzyme, which result from the conformational flexibility of the B', F, and G helices. Probes with properties similar to those of D-4-Ad potentially could be useful for screening P450 inhibitors.

Avian retrovirus DNA internal attachment site requirements for full-site integration in vitro

Concerted integration of retrovirus DNA termini into the host chromosome in vivo requires specific interactions between the cis-acting attachment (att) sites at the viral termini and the viral integrase (IN) in trans. In this study, reconstruction experiments with purified avian myeloblastosis virus (AMV) IN and retrovirus-like donor substrates containing wild-type and mutant termini were performed to map the internal att DNA sequence requirements for concerted integration, here termed full-site integration. The avian retrovirus mutations were modeled after internal att site mutations studied at the in vivo level with human immunodeficiency virus type 1 (HIV-1) and murine leukemia virus (MLV). Systematic overlapping 4-bp deletions starting at nucleotide positions 7, 8, and 9 in the U3 terminus had a decreasing detrimental gradient effect on full-site integration, while more internal 4-bp deletions had little or no effect. This decreasing detrimental gradient effect was measured by the ability of mutant U3 ends to interact with wild-type U3 ends for full-site integration in trans. Modification of the highly conserved C at position 7 on the catalytic strand to either A or T resulted in the same severe decrease in full-site integration as the 4-bp deletion starting at this position. These studies suggest that nucleotide position 7 is crucial for interactions near the active site of IN for integration activity and for communication in trans between ends bound by IN for full-site integration. The ability of AMV IN to interact with internal att sequences to mediate full-site integration in vitro is similar to the internal att site requirements observed with MLV and HIV-1 in vivo and with their preintegration complexes in vitro.

12-O-tetradecanoylphorbol-13-acetate (TPA)-induced c-Jun N-terminal kinase (JNK) phosphatase renders immortalized or transformed epithelial cells refractory to TPA-inducible JNK activity

c-Jun N-terminal kinase (JNK) regulates gene expression in response to various extracellular stimuli. JNK can be activated by the tumor promoting agent, 12-O-tetradecanoylphorbol-13-acetate (TPA) in normal human oral keratinocytes but not in human keratinocytes that have been immortalized (HOK-16B and HaCaT) or transformed (HOK-16B-Bap-T) nor in a cervical carcinoma cell line (HeLa). The refractory JNK activation response to TPA is not due a defect in the JNK pathway, because JNK can be activated by other stimuli, e.g. UV irradiation and an alkylating agent N-methyl-N'-nitrosoguanidine in these immortalized or transformed cells. More importantly, the refractory JNK and JNKK activation response to TPA can be restored by treatment of the cells with a combination of TPA and a protein-tyrosine phosphatase inhibitor, sodium orthovanadate. Furthermore, pretreatment of cells with TPA partially inhibited UV- or N-methyl-N'-nitrosoguanidine-induced JNK activity. These results suggest that a TPA-inducible, orthovanadate-sensitive protein-tyrosine phosphatase may specifically down-regulate JNK signaling pathway in these immortalized/transformed epithelial cells. In contrast, ERK and p38/Mpk2 are not regulated by this TPA-induced phosphatase. This putative protein-tyrosine phosphatase appears to be JNK pathway-specific.

ATF-2 has intrinsic histone acetyltransferase activity which is modulated by phosphorylation

Transcription factors carry functional domains, which are often physically distinct, for sequence-specific DNA binding, transcriptional activation and regulatory functions. The transcription factor ATF-2 is a DNA-binding protein that binds to cyclic AMP-response elements (CREs), forms a homodimer or heterodimer with c-Jun, and stimulates CRE-dependent transcription. Here we report that ATF-2 is a histone acetyltransferase (HAT), which specifically acetylates histones H2B and H4 in vitro. Motif A, which is located in the HAT domain, is responsible for the stimulation of CRE-dependent transcription; moreover, in response to ultraviolet irradiation, phosphorylation of ATF-2 is accompanied by enhanced HAT activity of ATF-2 and CRE-dependent transcription. These results indicate that phosphorylation of ATF-2 controls its intrinsic HAT activity and its action on CRE-dependent transcription. ATF-2 may represent a new class of sequence-specific factors, which are able to activate transcription by direct effects on chromatin components.

The E7 oncoprotein of human papillomavirus type 16 interacts with F-actin in vitro and in vivo

We report here that E7 oncoprotein of human papillomavirus type 16 (HPV-16) forms a complex in vivo and in vitro with actin, one of the components of the cellular cytoskeleton. The in vivo interaction was detected by immunofluorescent staining and confocal microscopic examination of normal human oral keratinocytes (NHOK) and CV-1 cells after transient expression of E7 employing the vaccinia virus-T7 RNA polymerase system and by coimmunoprecipitation from an immortalized, nontumorigenic cell line obtained after transfecting NHOK with the cloned HPV-16 DNA genome. The in vitro interaction was detected by cosedimentation of bacterially expressed E7 phosphorylated with rabbit reticulocyte lysate or purified casein kinase II (CKII) prior to incubation with F-actin. This interaction was inhibited if E7 phosphorylation by the rabbit reticulocyte lysate was prevented with heparin, a CKII inhibitor, or if the amino acids Ser-31 and Ser-32 in E7, which are phosphorylated by CKII, were replaced with amino acids that cannot be phosphorylated. Interestingly, a decrease in the amount of polymerized actin occurred in cells expressing E7.

Residual bladder dysfunction 2 to 10 years after acute transverse myelitis

OBJECTIVE

Acute transverse myelitis (ATM) is a relatively rare condition in children. The recovery rate is reported to be generally complete. In the current study, the long-term urological outcome of children with ATM was assessed.

METHODOLOGY

The medical records of children with ATM admitted to Queen Mary Hospital, Hong Kong, over the last 15 years, were reviewed.

RESULTS

The median age of the five children with ATM at the time of onset was 6 years (range = 2-12 years). The median length of follow up was 5 years (2-10 years). Four children recovered completely from paraparesis; two had no urinary symptoms with normal micturition. However, video-urodynamic studies 3 years after the acute onset revealed that four out of the five children, including one without any urinary symptom, suffered from residual bladder dysfunction - two from contractile neurogenic bladder and two from intermediate type of neurogenic bladder.

CONCLUSION

Residual bladder dysfunction is common in children suffering from ATM despite improvement of paraparesis and apparent lack of urological symptoms. Long-term follow up of urological function in these patients is recommended.

Retrovirus DNA termini bound by integrase communicate in trans for full-site integration in vitro

Integration of linear retrovirus DNA involves the concerted insertion of the viral termini (full-site integration) into the host chromosome. We investigated the interactions that occur between long terminal repeat (LTR) termini bound by avian retrovirus integrase (IN) for full-site integration in vitro. Wild-type (wt) or mutant LTR donors that possess gain-of-function ("G") or loss-of-function ("L") for full-site integration activity were used. G LTR termini are characterized as having significantly higher strand transfer activity than the wt and the L LTR termini. L LTR mutations are classified as partially or extremely defective for strand transfer activity. The L mutations were further classified by their ability to either permit or block the assembly of G or wt LTR termini into nucleoprotein complexes capable of full-site strand transfer. We demonstrated that avian myeloblastosis virus IN bound to G LTR termini increased the incorporation of partially defective L LTR termini into nucleoprotein complexes that were capable of full-site integration. The observed full-site integration activity of these assembled nucleoprotein complexes appeared to be influenced by each individual IN-LTR complex in trans. In contrast, extremely defective L LTR termini exhibited the ability to effectively block the assembly of wt LTR termini into nucleoprotein complexes capable of full-site strand transfer. Data from nonspecific DNA competition experiments suggested that IN had an apparent higher affinity for G LTR donor termini than for partially defective L LTR donor termini as measured by full-site integration activity. However, assembled nucleoprotein complexes containing either two G or two L LTR donors were stable, having a similar half-life of approximately 2 h on ice. The results suggest that LTR termini bound by IN exhibit an allosteric effect to modulate full-site integration in vitro. Similar regulatory controls also appear to exist in vivo between the wt U3 and wt U5 LTR termini in retroviruses as well as purified retrovirus preintegration complexes that promoted full-site integration in vitro.

Cutaneous rat wounds express c49a, a novel gene with homology to the human melanoma differentiation associated gene, mda-7

We have used DD-PCR (differential display-polymerase chain reaction) to identify new genes that are over- or underexpressed during wound repair. DD-PCR performed on excisional wounds identified the expression of rat c49a. Cloning and sequence analysis of the rat c49a gene revealed high homology to a novel human melanoma differentiation associated gene, mda-7. The human mda-7gene isolated from melanoma cell lines, has been linked with human melanoma differentiation, and growth suppression. Moreover, transfection of human mda-7 constructs into human tumor cells suppresses the growth and colony formation of tumor cells from diverse origins. To confirm and relatively quantitate expression of rat c49a gene during repair, specific primer, reduced cycle RT-PCR (reverse transcription-PCR) was performed. RT-PCR showed an approximately 9 to 12-fold elevation of rat c49a mRNA at 12 h to 5 days above nonwounded controls that gradually decreased to approximately 1.5 to 3-fold by day 14. Cloning and sequence analysis of the entire 1200 base pair c49a gene product showed 78% nucleotide homology to human mda-7. Immunohistochemistry studies localized rat C49A expression primarily to fibroblast-like cells at the wound edge and base. The marked up-regulation of rat c49a transcripts during the inflammatory and early granulation tissue phases of wound repair where cellular processes such as re-epithelialization, angiogenesis, and fibroplasia predominate--suggest that c49a is associated with proliferation of fibroblasts in wound healing.