The UK Divide: Does Having a Pembrolizumab-Chemotherapy Option in Head and Neck Cancer Matter? Real-world Experience of First-line Palliative Pembrolizumab Monotherapy and Pembrolizumab-Chemotherapy Combination in Scotland

AIMS

The Scottish Medical Consortium recently approved first-line pembrolizumab monotherapy or in combination with chemotherapy for head and neck squamous cell carcinoma in the palliative setting, contrasting with the decision made by the National Institute for Health and Care Excellence, who approved monotherapy alone in England and Wales. The aim of this study was to provide real-world performance data for first-line pembrolizumab-containing treatments for head and neck squamous cell carcinoma in the palliative setting in Scotland.

MATERIALS AND METHODS

We analysed the electronic records of patients who started pembrolizumab-containing treatment between 1 March 2020 and 30 September 2021. Outcomes included overall survival, progression-free survival (PFS), the duration of response and the disease control rate. Data were compared with the KEYNOTE-048 study and clinical factors were evaluated for association with survival.

RESULTS

Our cohort included 91 patients (median follow-up 10.8 months). Patient characteristics were similar to those in the KEYNOTE-048 study, although our cohort had a higher proportion of patients with newly diagnosed, non-metastatic disease. For patients receiving monotherapy (n = 76), 12- and 24-month overall survival were 45% and 27%, respectively. For patients receiving pembrolizumab-chemotherapy (n = 15), 12-month overall survival was 60% (24-month overall survival had not yet been reached). Experiencing one or more immune-related adverse event (irAE; versus no irAEs), of any grade, was associated with favourable overall survival and PFS for patients receiving monotherapy in both univariable Log-rank analysis (median overall survival 17.4 months versus 8.6 months, respectively, P = 0.0033; median PFS 10.9 months versus 3.0 months, respectively, P < 0.0001) and multivariable analysis (Cox proportional hazards regression: overall survival hazard ratio 0.31, P = 0.0009; PFS hazard ratio 0.17, P < 0.0001).

CONCLUSION

Our real-world data support the KEYNOTE-048 study findings and the value of combination treatment options. Additionally, our data show that irAEs of any grade, as reported in routine clinical records, are associated with better outcomes in this patient group, adding to the growing body of evidence showing that irAEs are generally a positive marker of programmed death-ligand 1 (PD-L1) inhibitor response.

Neoadjuvant tyrosine kinase inhibitor therapy in locally advanced differentiated thyroid cancer: a single centre case series

OBJECTIVE

Primary surgical resection remains the mainstay of management in locally advanced differentiated thyroid cancer. Tyrosine kinase inhibitors have recently shown promising results in patients with recurrent locally advanced differentiated thyroid cancer. This study discussed four patients with locally advanced differentiated thyroid cancer managed with tyrosine kinase inhibitors used prior to surgery in the 'neoadjuvant' setting.

METHOD

Prospective data collection through a local thyroid database from February 2016 identified four patients with locally advanced differentiated thyroid cancer unsuitable for primary surgical resection commenced on neoadjuvant tyrosine kinase inhibitor therapy.

RESULTS

All cases had T4a disease at presentation. Three cases tolerated tyrosine kinase inhibitor therapy for more than 14 months while the last case failed to tolerate treatment at 1 month. All patients subsequently underwent total thyroidectomy to facilitate adjuvant radioactive iodine treatment. Disease-specific survival remains at 100 per cent currently (range, 29-75 months).

CONCLUSION

Neoadjuvant tyrosine kinase inhibitors in locally advanced differentiated thyroid cancer can be effective in reducing primary tumour extent to potentially facilitate a more limited surgical resection for local disease control.

A Multicenter Study of Clinician and Patient Reported Acute and Late Toxicity after Radical (Chemo)Radiotherapy for Non-Endemic Nasopharyngeal Cancer

PURPOSE/OBJECTIVE(S)

Curative (chemo)radiotherapy ((CT)RT) for Nasopharyngeal cancers (NPC) achieves excellent disease control but is associated with significant late toxicities despite modern treatment delivery. Contemporary late toxicity data, including patient reported outcomes (PROs), is limited in the non-endemic population; we present a large contemporary series of toxicity outcomes and late PROs following treatment of non-endemic NPC.

MATERIALS/METHODS

Adult patients completing radical (CT)RT for primary NPC between February 2016 and 2020 at 7 large UK cancer centers were identified on institutional databases. Patients were excluded if they had prior head and neck cancer or prior therapeutic head and neck surgery (except neck dissection). Patients with an active other cancer were excluded from PRO assessment. Demographic, treatment, acute toxicity and outcome data were collected retrospectively from patient records. Disease-free patients were invited to complete an M.D. Anderson Dysphagia Index (MDADI) and University of Washington (UoW) Quality of Life (QoL) PROs questionnaires.

RESULTS

A total of 180 eligible patients were identified: 68% male, median age 54 years, 11% ≥70 years. EBV status was positive in 61% (unknown 12%). Patients had stage I (5%), II (22%), III (37%), IV (36%) disease; 95% were performance status ≤1 at baseline. Median follow-up was 31.2 months (range 0-68). A total of 54% received 70Gy in 33-35# and 43% received 65-66 Gy in 30-33#. 66% received induction and 65% received concurrent chemotherapy. 9.5% had residual disease at the first follow-up scan. Subsequent locoregional or distant recurrence occurred in 5% and 12% respectively. At last assessment, 84% patients were alive, 16% had died (of which 70% had active disease). Acute treatment toxicity included: 63% of patients required enteral support (median duration 98 days) with 9% a feeding tube at 1 year post treatment. 18% G3 dermatitis, 53% G3 mucositis. 82% requiring opioids and 40% admitted for symptom management. 90 patients completed the PROs (76% response rate) at a median of 37.8 months post treatment (Table 1). These demonstrate significant QoL detriment: 28% report significant pain, 24% require regular analgesia, and 59% report significant impact on daily activity. This was found to persist at different timepoints (not shown).

CONCLUSION

Excellent cancer survival outcomes are seen in a non-selected, non-endemic NPC population. However significant acute and late toxicity following radical treatment is identified which can profoundly negatively impact QoL in a relatively young cohort. This highlights the importance of ongoing efforts to reduce toxicity and supports the prospective evaluation of potential toxicity sparing technologies, such as proton beam radiotherapy.

Intensive Blood Pressure Management Preserves Functional Connectivity in Patients with Hypertension from the Systolic Blood Pressure Intervention Randomized Trial

BACKGROUND AND PURPOSE

The Systolic Blood Pressure Intervention (SPRINT) randomized trial demonstrated that intensive blood pressure management resulted in slower progression of cerebral white matter hyperintensities, compared with standard therapy. We assessed longitudinal changes in brain functional connectivity to determine whether intensive treatment results in less decline in functional connectivity and how changes in brain functional connectivity relate to changes in brain structure.

MATERIALS AND METHODS

Five hundred forty-eight participants completed longitudinal brain MR imaging, including resting-state fMRI, during a median follow-up of 3.84 years. Functional brain networks were identified using independent component analysis, and a mean connectivity score was calculated for each network. Longitudinal changes in mean connectivity score were compared between treatment groups using a 2-sample t test, followed by a voxelwise t test. In the full cohort, adjusted linear regression analysis was performed between changes in the mean connectivity score and changes in structural MR imaging metrics.

RESULTS

Four hundred six participants had longitudinal imaging that passed quality control. The auditory-salience-language network demonstrated a significantly larger decline in the mean connectivity score in the standard treatment group relative to the intensive treatment group (P = .014), with regions of significant difference between treatment groups in the cingulate and right temporal/insular regions. There was no treatment group difference in other networks. Longitudinal changes in mean connectivity score of the default mode network but not the auditory-salience-language network demonstrated a significant correlation with longitudinal changes in white matter hyperintensities (P = .013).

CONCLUSIONS

Intensive treatment was associated with preservation of functional connectivity of the auditory-salience-language network, while mean network connectivity in other networks was not significantly different between intensive and standard therapy. A longitudinal increase in the white matter hyperintensity burden is associated with a decline in mean connectivity of the default mode network.

A Case Report of Hereditary Palmoplantar Keratoderma with Esophageal Melanosis

A 70-year-old man, a known case of diabetes mellitus since 10 years ago, presented with lower limb swelling and dyspnea on exertion for one month and dysphagia to solids associated with early satiety for 2 weeks. The patient had palmoplantar keratosis (PPK), which was present since birth with a similar family history. The patient was admitted to rule out esophageal malignancy. Upper gastrointestinal gastroscopy revealed esophagitis and esophageal melanosis with gastric mucosal erythema. Biopsies samples were taken. Histopathological examination revealed reflux esophagitis and chronic active Helicobacter pylori gastritis with no evidence of malignancy. His symptoms improved following H. pylori eradication and treatment for coronary artery disease and heart failure. The patient was advised of regular follow-up as he had risk factors for the development of esophageal melanoma or squamous cell carcinoma.

Building capacity for cancer care infrastructure in Karnataka - the present and the future

BACKGROUND

Cancer mortality has doubled in India, a lower and middle-income country, from 1990 to 2016, depicting the ever-increasing burden of non-communicable disease. Karnataka, situated in the south of India, is one of the states with a rich medical college and hospital milieu. We present the status of cancer care across the state from the data collected by the investigators through public registries and personal communication to the concerned units to know the distribution of various services across the districts and give probable directives to improve on the present situation with emphasis on radiation therapy. This study may be taken as a bird's eye view of the situation across the country and form a basis based on which future planning of services and areas to emphasize on, may be considered.

PURPOSE

The establishment of a radiation therapy center holds the key to the establishment of comprehensive cancer care centers. The existing situation of such centers and the need and scope for inclusion and expansion of cancer units is presented in this article.

Comparison of Fasting Insulin Level, Homeostatic Model of Insulin Resistance, and Lipid Levels between Patients with Primary Hypertension and Normotensive Subjects

BACKGROUND

Hyperinsulinemia and insulin resistance occurs in obese patients with primary hypertension independent of diabetes and obesity. This study was aimed at assessing serum fasting insulin levels, the homeostatic model assessment for insulin resistance (HOMA-IR), and serum lipid levels in non-obese patients with primary hypertension when compared to normotensive subjects.

METHODS

This observational study comprised 100 patients over 18 years of age, divided into two groups. The hypertensive group comprised non-obese patients with primary hypertension (n=50); the normotensive group comprised normotensive age- and sex-matched individuals (n=50). Patients with diabetes, impaired fasting glucose, obesity, and other causative factors of insulin resistance were excluded from the study. Serum fasting insulin levels and fasting lipid profiles were measured, and insulin resistance was calculated using HOMA-IR. These data were compared between the two groups. Pearson's correlation coefficient was used to assess the extent of a linear relationship between HOMA-IR and to evaluate the association between HOMA-IR and systolic and diastolic blood pressures.

RESULTS

Mean serum fasting insulin levels (mIU/L), mean HOMA-IR values, and fasting triglyceride levels (mg/dL) were significantly higher in the hypertensive versus normotensive patients (10.32 versus 6.46, P<0.001; 1.35 versus 0.84, P<0.001; 113.70 versus 97.04, P=0.005, respectively). The HOMA-IR levels were associated with systolic blood pressure (r value 0.764, P=0.0005).

CONCLUSION

We observed significantly higher fasting insulin levels, serum triglyceride levels, and HOMA-IR reflecting hyperinsulinemia and possibly an insulin-resistant state among primary hypertension patients with no other causally linked factors for insulin resistance. We observed a significant correlation between systolic blood pressure and HOMA-IR.

EBV-positive mucocutaneous ulceration

Ulceration of the oral cavity is common and a frequent reason for referral to secondary and tertiary centres. Epstein-Barr virus (EBV)-related mucocutaneous ulceration, however, is a rare cause of oral ulceration that has been described only recently. Histologically these lesions resemble lymphomas; however, their management and prognosis differ significantly. We present a case of EBV-induced oral ulceration and discuss the diagnosis and management of and available literature for the condition, which was treated successfully through conservative measures alone.

The requirement of hemodialysis in patients with acute gastroenteritis-induced acute kidney injury

Acute gastroenteritis is an important cause of preventable acute kidney injury (AKI). Inadequate or delayed restoration of diarrheal losses results in a very high incidence of AKI. Diarrheal illness is a major reason for hospitalization, but data on consequent acute kidney injury are sparse. The objective of the study is to determine the incidence of AKI in infectious and noninfectious diarrheal illness requiring hospitalization and to identify correlates and outcomes of diarrhea-associated AKI. None of the patients had any organism isolated in stool, probably due to prompt initiation of antibiotics/inadequate culture growth. Three out of our 6 cases did not require hemodialysis (HD) and AKI resolved on conservative management alone (fluids, electrolyte management, and antibiotics). Three out of 6 cases had nonresolving AKI and were dependent on renal replacement therapy (RRT) even at 1 month after discharge as they remained oliguric. One recent paper has reported the recovery of renal function after a period of dialysis. Frequent electrolyte abnormalities, risk of (catheter-related/bloodstream) infections, and severity of the primary disease are the chief reasons for the persistently high morbidity. Although, there was no mortality in our study.

GeneXpert assay - A cutting-edge tool for rapid tissue diagnosis of tuberculous lymphadenitis

BACKGROUND

The most prevalent clinical entity of extra pulmonary tuberculosis is tuberculous lymphadenitis. However, it resembles other granulomatous conditions pathologically and obtaining tissue for microbiological diagnosis is also difficult. Thus it is a challenging task for diagnosis and early initiation of management. Fine needle aspiration cytology and biopsy are the diagnostic methods generally used to obtain the lymph node samples for histopathological and microbiological diagnosis. Mycobacterium culture on Lowenstein-Jensen medium remains the gold standard for definitive diagnosis, but its major limitations is a prolonged turn-around time of 2-4 weeks. The GeneXpert Mtuberculosis/RIF assay is a novel molecular diagnostic method for rapid diagnosis of tuberculosis and rifampicin resistance in clinical specimens.

METHODS

This was a cross sectional analytical study conducted on 67 cases of suspected tubercular lymphadenitis at R.L Jalappa Hospital and Research Centre, Tamaka, Kolar. The study was carried out between December 2017 to June 2019. The samples were collected using excision biopsy and subjected to GeneXpert Mtuberculosis/RIF assay and histopathology. Further, sensitivity, specificity, positive predictive value and negative predictive value was measured and compared with histopathology.

RESULTS

The average age of the patients was 37.04 ± 19.27 and majority was males. The lymph nodes were predominantly present in cervical region. Histopathology analysis reveals 46 positive cases of tuberculosis Lymphadenitis and GeneXpert Mtuberculosis/RIF assay detects 42 cases of tuberculosis Lymphadenitis. In the present study, GeneXpert Mtuberculosis/RIF assay had a sensitivity of 82.60% and specificity of 85% when compared to histopathology. Further the PPV and NPV was found to be 92.68% and 68% respectively. GeneXpert Mtuberculosis/RIF showed 2 cases of rifampicin resistance out of 67 cases. In this study, the GeneXpert Mtuberculosis/RIF showed the results in 0.79 days.

CONCLUSION

The present study showed that GeneXpert Mtuberculosis/RIF is a simple and reliable technique for diagnosing tuberculosis Lymphadenitis with high specificity and sensitivity as compared histopathology. Further, the methods elicit rapid diagnosis and also detected rifampicin resistance. It is thus a reliable and useful diagnostic modality in rapid detection of the causative agent and initiation of appropriate category anti-tubercular therapy when necessary.

Gender and limb differences in temporal gait parameters and gait variability in ankle osteoarthritis

BACKGROUND

The effects of ankle osteoarthritis on gait are noticeable in the clinic, but are difficult to quantify and score without detailed kinematic and kinetic analysis. Evaluationof temporal gait parameters and gait variability is a potential alternative.

RESEARCH QUESTION

This study aimed to determine associations between limb and gender with temporal gait parameters and gait variability in ankle OA patients to evaluate the utility of these parameters for gait assessment in a clinical setting.

METHODS

Following informed consent, 242 end-stage unilateral ankle OA patients walked at self-selected speed across force plates. Means and stride-to-stride standard deviations (SD) of stride, swing, stance, and double support times were determined for each patient. Limb x Gender ANCOVA models co-varying for walking speed were run for swing and stance times, while stride and double support times were only compared between genders. Statistical analysis was performed in SPSS (α = 0.05).

RESULTS

Walking speed affected all measures of interest. After adjusting for walking speed, mean stride time, stride time SD, and stance time SD were 3.5%, 67% and 29% higher among women than men (p = 0.002, 0.035 and 0.02 respectively). Swing time was 12% higher and stance time was 6% lower on the affected side compared to the unaffected side (p < 0.001 for both).

SIGNIFICANCE

Women have longer stride times and higher variability, which may indicate higher fall risk. Both genders minimized loading on the affected limb by increasing swing time and reducing stance time on the affected side. Simple, easy to record temporal gait patterns can provide useful insight into gait abnormalities in patients with ankle OA.

c-Abl and Arg are activated in human primary melanomas, promote melanoma cell invasion via distinct pathways, and drive metastatic progression

Despite 35 years of clinical trials, there is little improvement in 1-year survival rates for patients with metastatic melanoma, and the disease is essentially untreatable if not cured surgically. The paucity of chemotherapeutic agents that are effective for treating metastatic melanoma indicates a dire need to develop new therapies. Here, we found a previously unrecognized role for c-Abl and Arg in melanoma progression. We demonstrate that the kinase activities of c-Abl and Arg are elevated in primary melanomas (60%), in a subset of benign nevi (33%) and in some human melanoma cell lines. Using siRNA and pharmacological approaches, we show that c-Abl/Arg activation is functionally relevant because it is requiredfor melanoma cell proliferation, survival and invasion. Significantly, we identify the mechanism by which activated c-Abl promotes melanoma invasion by showing that it transcriptionally upregulates matrix metalloproteinase-1 (MMP-1), and using rescue approaches we demonstrate that c-Abl promotes invasion through a STAT3 → MMP-1 pathway. Additionally, we show that c-Abl and Arg are not merely redundant, as active Arg drives invasion in a STAT3-independent manner, and upregulates MMP-3 and MT1-MMP, in addition to MMP-1. Most importantly, c-Abl and Arg not only promote in vitro processes important for melanoma progression, but also promote metastasis in vivo, as inhibition of c-Abl/Arg kinase activity with the c-Abl/Arg inhibitor, nilotinib, dramatically inhibits metastasis in a mouse model. Taken together, these data identify c-Abl and Arg as critical, novel, drug targets in metastatic melanoma, and indicate that nilotinib may be useful in preventing metastasis in patients with melanomas harboring active c-Abl and Arg.

Multidrug resistant tuberculosis co-existing with aspergilloma and invasive aspergillosis in a 50 year old diabetic woman: a case report

Aspergilloma and invasive aspergillosis coexisting with multidrug resistant Mycobacterium tuberculosis (MDR-TB) in the same patient is a rare entity. We report a 50 year old South Indian woman, a diabetic, who presented to us with complaints of productive cough and hemoptysis for the past 2 months. She was diagnosed to have pulmonary tuberculosis 2 years ago for which she took irregular treatment. Lung imaging showed features of a thick walled cavity in the right upper lobe with an indwelling aspergilloma. She underwent a right lung upper lobe resection. Biopsy and culture of the resected specimen showed the coexistence of Aspergillus fumigatus and multi-drug resistant Mycobacterium tuberculosis. 2 blood cultures grew Aspergillus fumigatus. She was successfully treated with Voriconazole and anti tuberculous therapy against MDR-TB.

Reduced multivariate polynomial-based neural network for automated traffic incident detection

This paper proposes a neural network model based on reduced multivariate polynomial pattern classifier for application in freeway incident detection. The reduced multivariate model (RM) is a recently proposed classifier model which is easy to implement and analyze, and has been observed to efficiently capture the nonlinear input-output relationships in many classification applications. Since the freeway incident detection can be treated as a two-category pattern classification problem, the reduced multivariate polynomial model is particularly suitable for this incident detection application. Both Recursive Singular Value Decomposition (RSVD)-based and gradient descent-based least square estimators were adopted to learn the RM classifier in this work. The comparison of results obtained with those from several other classification strategies demonstrates the efficacy of the proposed model for traffic incident detection.

Aggressive breast cancer cells are dependent on activated Abl kinases for proliferation, anchorage-independent growth and survival

Mutant Abl kinases (such as BCR-Abl) drive the development of leukemia; however little is known regarding whether Abl kinases contribute to the development or progression of solid tumors. We recently demonstrated that endogenous Abl kinases (c-Abl, Arg) are activated by deregulated ErbB receptors and Src kinases, and drive invasion of aggressive breast cancer cells. In this study, we examined whether activation of endogenous Abl kinases affects transformation, proliferation and survival, which are major contributors to breast cancer development and metastatic progression. Using a pharmacological inhibitor and RNAi, we demonstrate that activation of endogenous Abl kinases dramatically promotes breast cancer cell proliferation and anchorage-independent growth in serum, as well as survival following nutrient deprivation. Activation of Abl kinases mediates phosphorylation of STAT3, and promotes proliferation by accelerating G(1) --> S progression. Moreover, we identify IGF-1R as a novel upstream activator of endogenous Abl kinases, and demonstrate that Abl kinase activation is required for IGF-1-stimulated cell cycle progression in breast cancer cells. Since activation of Abl kinases affects multiple steps of breast cancer development and progression, Abl kinase inhibitors are likely to be effective agents for the treatment of breast cancers containing highly active Abl kinases.

Orofacial pain – a presenting symptom of bisphosphonate associated osteonecrosis of the jaws

Osteonecrosis of the jaws (ONJ) associated with bisphosphonate therapy is being reported with increasing frequency all over the world. Pain may be the presenting symptom commonly associated with intra-oral bone exposure. The aetiology of this therapeutic complication is still not well understood. Three cases are presented and the management of the condition is discussed.

Results of the centralisation of adult emergency oral and maxillofacial surgical services at the University Hospital, Birmingham

In 2001, the oral and maxillofacial surgical (OMFS) services for adults in Birmingham were centralised at the Selly Oak site of the University Hospital and the OMFS department was given access to the emergency operating theatre every day. We examined the effects of this on the emergency workload during the 6 months after centralisation and compared it with the emergency workload at the University Hospital during the 6 months before centralisation. The number of adult patients who attended the University Hospital as emergencies increased from 242 in the 6 months before centralisation to 545 in the subsequent 6 months (an increase of 127%). Of the latter 164 (30%) were admitted and operated on, 138 (84%) within 24h of admission. Despite the large increase in the number of patients, 102 (74%) were operated on during normal working hours. After centralisation, all operations were done on multidisciplinary emergency lists compared with only 55% before centralisation. Centralisation did not reduce the access of patients to the emergency service and conformed with the guidelines of the National Confidential Enquiry into Perioperative Deaths (NCEPOD).

Mutational analysis of the fruA promoter region demonstrates that C-Box and 5-base-pair elements are important for expression of an essential developmental gene of Myxococcus xanthus

Myxococcus xanthus uses extracellular signals during development to regulate gene expression. C-signaling regulates the expression of many genes induced after 6 h into development. FruA is a protein that is necessary for cells to respond to C-signaling, but expression of the fruA gene does not depend on C-signaling. Yet the fruA promoter region has a C box and a 5-bp element, similar to the promoter regions of several C-signal-dependent genes, where these sequences are crucial. Here, we show that the C box and 5-bp elements are important for expression of fruA, demonstrating for the first time that these sequences play a role in the expression of a gene that does not depend on C-signaling and is required for M. xanthus development.

Antimicrobial activity of certain Indian medicinal plants used in folkloric medicine

Fifty medicinal plants belonging to 26 families were studied for their antimicrobial activity. Among 50 plants tested, 72% showed antimicrobial activity. About 22 plant extracts from 15 families exhibited activity against both Gram-positive and Gram-negative bacteria. Fourteen plants belonging to 11 families did not show activity against any of the bacteria tested. Only nine plant extracts showed antifungal activity. The bulb extracts of A. cepa and A. sativum exhibited activity against both filamentous and non-filamentous fungus. Eight plant extracts belonging to seven families exhibited both antibacterial and antifungal activity.

Delayed reversal of shape change in cells expressing FP(B) prostanoid receptors. Possible role of receptor resensitization

Prostaglandin F(2 alpha) (PGF(2 alpha)) receptors are G-protein-coupled receptors consisting of two alternative mRNA splice variants, named FP(A) and FP(B). As compared with the FP(A) isoform, the FP(B) isoform lacks the last 46 amino acids of the carboxyl terminus and, therefore, represents a truncated version of the FP(A). We recently found (Pierce, K. L., Fujino, H., Srinivasan, D., and Regan, J. W. (1999) J. Biol. Chem. 274, 35944-35949) that stimulation of both isoforms with PGF(2 alpha) leads to activation of a Rho signaling pathway, resulting in tyrosine phosphorylation of p125 focal adhesion kinase, formation of actin stress fibers, and cell rounding. Although the activation of Rho and subsequent cell rounding occur at a similar rate for both isoforms, we now report that following the removal of PGF(2 alpha) the reversal of cell rounding is much slower for cells expressing the FP(B) isoform as compared with the FP(A) isoform. Thus, in HEK-293 cells that stably express the FP(A) isoform, the reversal of cell rounding appears to be complete after 1 h, whereas for FP(B)-expressing cells there is essentially no reversal even after 2 h. Similarly, the disappearance of stress fibers and dephosphorylation of p125 focal adhesion kinase following removal of agonist are much slower in FP(B)-expressing cells than in FP(A)-expressing cells. The mechanism of this differential reversal appears to involve a difference in receptor resensitization following the removal of agonist. Based upon whole cell radioligand binding, agonist-induced stimulation of inositol phosphate formation, and mobilization of intracellular Ca(2+), the FP(B) isoform resensitizes more slowly than the FP(A) isoform. These findings suggest that the carboxyl terminus of the FP(A) is critical for resensitization and that the slower resensitization of the FP(B) isoform leads to prolonged signaling. This differential signaling distinguishes the FP(A) and FP(B) receptor isoforms and could be important toward understanding the physiological actions of PGF(2 alpha).

Complete structural characterisation of the mammalian and Drosophila TRAF genes: implications for TRAF evolution and the role of RING finger splice variants

The complete murine TRAF2 gene was obtained using a lambda phage and PCR cloning strategy. The gene was found to consist of ten coding and one 5' non-coding exon spread over 28 kbp of DNA. We also report the basic structure of the human TRAF5 and TRAF6 genes obtained by analysis of the genomic DNA database. Comparison of these three gene structures, along with those previously described for TRAF1, TRAF3 and TRAF4, revealed the evolutionary relationship between the six known mammalian TRAFs. The TRAF1/TRAF2 and TRAF3/TRAF5 gene pairs were found to have arisen from recent independent gene duplications and to share a common ancestral gene. Specific TRAF4 and TRAF6 precursor genes were found to have arisen earlier during evolution, with the divergence of the TRAF6 precursor occuring earliest of all. The Drosophila genome was found to contain three TRAF family genes: dTRAF1, dTRAF6 (dTRAF2) and a previously undescribed member we have designated dTRAF3. TRAF-C domain homology indicated that dTRAF3 is likely to have derived from the common precursor for the TRAF 1, 2, 3 and 5 genes, whilst dTRAF1 and dTRAF6 have derived from the TRAF4 and TRAF6 precursor genes, respectively. The implication of these results for the functional evolution of TRAFs is discussed. Analysis is also presented of the conservation of the TRAF2A molecule, a TRAF2 alternate splice isoform with an extended RING finger domain previously described in mice. TRAF2A was not found to be encoded by the human or rat TRAF2 genes and no other murine TRAF gene was found to produce a similar alternate splice product. We also report that the sequence of murine C57BL/6 TRAF4 differs significantly from the published murine TRAF4 sequence, but appears to represent the actual TRAF4 sequence expressed in many mouse strains.

Apoptotic response to growth factor deprivation involves cooperative interactions between c-Fos and p300

Two preneoplastic cell lines have been utilized to study changes in the regulation of apoptosis during neoplastic progression [sup+I (stage I) and sup-II (stage II)]. Sup+I cells are prone to undergo apoptosis, while sup-II cells are relatively resistant. We report that induction of apoptosis in sup+I cells is tightly correlated with the formation of c-Fos/p300 complexes, which were not present in the non-apoptotic sup-II cells under the same conditions. When apoptosis was induced in the sup-II cells by over-expression of c-Fos, concomitant c-Fos:p300 complexes were detected. Over-expression of p300 resulted in apoptosis in sup-II cells and also in p53wt human tumor cells, but not in p53mutant human tumor cells. Over-expression of the C-terminal fragment of p300, which contains the c-Fos binding site, enhanced apoptosis, suggesting that the c-Fos:p300 complex is actively involved in apoptosis. We propose that p300 could function as a general mediator of transcription factor-induced apoptosis.

Differential regulation of prostaglandin F(2alpha) receptor isoforms by protein kinase C

Prostaglandin F(2alpha) receptors (FP) are G protein-coupled receptors that bind prostaglandin F(2alpha) (PGF(2alpha)), resulting in the activation of an inositol phosphate (IP) second messenger pathway. Alternative mRNA splicing generates two FP receptor isoforms. These isoforms, designated FP(A) and FP(B), are otherwise identical except for their carboxyl termini. FP(B) is essentially a truncated version of FP(A) that lacks the 46 carboxyl-terminal amino acids, including four putative protein kinase C (PKC) phosphorylation sites. Until now, functional differences between these FP receptor isoforms have not been identified. We now report that pretreatment with the PKC inhibitor bisindolylmaleimide I enhanced PGF(2alpha)-stimulated IP accumulation in transfected cells stably expressing the FP(A) isoform but not in cells stably expressing the FP(B) isoform. Whole-cell phosphorylation experiments showed a strong agonist-dependent phosphorylation of the FP(A) isoform but little or no phosphorylation of the FP(B). Pretreatment of cells with bisindolylmaleimide I decreased PGF(2alpha)-stimulated phosphorylation of the FP(A) isoform consistent with a PKC-dependent phosphorylation. In vitro phosphorylation of an FP(A) carboxyl-terminal fusion protein by recombinant PKCalpha showed that the carboxyl terminus of the FP(A) is a substrate for PKC. These results suggest that PKC-dependent phosphorylation is responsible for differential regulation of second messenger signaling by FP prostanoid receptor isoforms.

Activation of FP prostanoid receptor isoforms leads to Rho-mediated changes in cell morphology and in the cell cytoskeleton

Prostaglandin F(2alpha) (PGF(2alpha)) exerts its biological effects by binding to and activating FP prostanoid receptors. These receptors, which include two isoforms, the FP(A) and FP(B), have been cloned from a number of species and are members of the superfamily of G-protein-coupled receptors. Previous studies have shown that the activation of FP receptors leads to phosphatidylinositol hydrolysis, intracellular calcium release, and activation of protein kinase C. Here, we demonstrate that PGF(2alpha) treatment of 293-EBNA (Epstein-Barr nuclear antigen) cells that have been stably transfected with either the FP(A) or FP(B) receptor isoforms leads to changes in cell morphology and in the cell cytoskeleton. Specifically, cells treated with PGF(2alpha) show retraction of filopodia and become rounded, and actin stress fibers are formed. Pretreatment of the cells with bisindolylmaleimide I, a protein kinase C inhibitor, has no effect on the PGF(2alpha)-induced changes in cell morphology, although it does block the effects of phorbol myristate acetate on cell morphology. On the other hand, the PGF(2alpha)-induced changes in cell morphology and formation of actin stress fibers can be blocked by pretreatment of the cells with C3 exoenzyme, a specific inhibitor of the small G-protein, Rho. Consistent with FP receptor induced formation of actin stress fibers and focal adhesions, FP(A) receptor activation also leads to rapid (within two minutes) tyrosine phosphorylation of p125 focal adhesion kinase (FAK) which can be blocked by pretreating the cells with C3 exoenzyme. Taken together, these results suggest that the FP receptor isoforms are coupled to at least two second messenger pathways, one pathway associated with protein kinase C activation, and the other with activation of Rho.

Inhibition of tetrahydroisoxazolo-pyridin-3-ol and muscimol and its mechanism on gastrointestinal transit in mice

The effect of tetrahydroisoxazolo-pyridin-3-ol (THIP) and muscimol on gastrointestinal transit and a possible mechanism for this effect were studied using the charcoal meal test in mice. These agents inhibited transit dose relatedly. The inhibitory effect was completely reversed by yohimbine and phentolamine. A minor degree of antagonism by bicuculline was observed. There were an additive response in morphine-pretreated animals and partial antagonism in naloxone-pretreated animals. Propranolol failed to modify the inhibitory effect. The findings suggest a predominantly alpha 2-receptor-mediated inhibitory effect on gastrointestinal transit for THIP and muscimol which possibly also utilizes opioid pathways. However, it appears that beta-adrenergic and GABAergic systems might not contribute to this effect.

Tolerance pattern to GABAmimetic analgesics and their influence on morphine tolerance and dependence

The possible development of acute and chronic tolerance to 4, 5, 6, 7-tetrahydroisoxazole-(5, 4-C)pyridin-3-ol (THIP) and muscimol-induced analgesia was tested using the acetic acid induced writhing assay. Acute tolerance developed to their analgesic actions on repeated exposure at a 4-h interval which was sensitive to naloxone. Chronic tolerance gradually developed to these agents from the 4th day and was appreciable after 10 days of treatment. Injection of THIP or muscimol prior to morphine attenuated the acute tolerance developed to morphine analgesia. These findings reveal that acute and chronic tolerance developed to THIP and muscimol induced analgesia and are suggestive of a role for opioidergic system in the development of acute tolerance to their analgesic effect. However, these agents per se did not produce any dependence phenomena and failed to affect morphine dependence indicating that different mechanisms might be operating in the development of tolerance and dependence.