The cross-sectional association between diabetes and orthostatic hypotension in community-dwelling older people.

AIMS: Orthostatic hypotension is a recognized complication of diabetes, but studies examining prevalence in diabetes are limited. The aim of this study was to ascertain the prevalence of orthostatic hypotension and the pattern of orthostatic BP response in a cohort of people with diabetes aged ≥ 50 years, embedded within the Irish Longitudinal Study of Ageing. METHODS: Orthostatic hypotension was defined as a drop in systolic blood pressure (SBP) ≥ 20 mmHg or drop in diastolic blood pressure (DBP) ≥ 10 mmHg at 30 s after standing. Diabetes was defined by self-report but cross-checked against HbA1c and medication records. Multilevel mixed effects linear regression models were used to compare orthostatic BP in people with and without diabetes. RESULTS: Some 3222 people were included, 7% (213 of 3222) of whom had diabetes. Prevalence of orthostatic hypotension in the group with diabetes was 22% (46 of 213) vs. 13% in those without diabetes; χ2 = 12.43; P < 0.001. Multilevel models demonstrated prolonged recovery of DBP in people with diabetes, with only 41% (87 of 213) returning to baseline by 60 s. Logistic regression models demonstrated that diabetes was associated with a significantly increased likelihood of orthostatic hypotension (odds ratio 1.84, 95% confidence interval 1.30-2.59; P = 0.001) and this remained robust after controlling for covariates. CONCLUSION: Over one-fifth of older people with diabetes had orthostatic hypotension. Recovery of DBP is related to dynamic changes in total peripheral resistance and impairment of this baroreflex-mediated response may explain the higher prevalence in diabetes. Given the prognostic implications when co-existing with diabetes, orthostatic hypotension may represent a potentially modifiable risk factor for adverse outcomes in late-life diabetes.

Measuring the impact of oesophagectomy on physical functioning and physical activity participation: a prospective study.

BACKGROUND: Oesophagectomy remains the only curative intervention for oesophageal cancer, with defined nutritional and health-related quality of life (HR-QOL) consequences. It follows therefore that there is a significant risk of decline in physical wellbeing with oesophagectomy however this has been inadequately quantified. This study prospectively examines change in physical functioning and habitual physical activity participation, from pre-surgery through 6-months post-oesophagectomy. METHODS: Patients scheduled for oesophagectomy with curative intent were recruited. Key domains of physical functioning including exercise tolerance (six-minute walk test (6MWT)) and muscle strength (hand-grip strength), and habitual physical activity participation, including sedentary behaviour (accelerometry) were measured pre-surgery (T0) and repeated at 1-month (T1) and 6-months (T2) post-surgery. HR-QOL was measured using the EORTC-QOL C30. RESULTS: Thirty-six participants were studied (mean age 62.4 (8.8) years, n = 26 male, n = 26 transthoracic oesophagectomy). Mean 6MWT distance decreased significantly from T0 to T1 (p = 0.006) and returned to T0 levels between T1 and T2 (p < 0.001). Percentage time spent sedentary increased throughout recovery (p < 0.001) and remained significantly higher at T2 in comparison to T0 (p = 0.003). In contrast, percentage time spent engaged in either light or moderate-to-vigorous intensity activity, all reduced significantly (p < 0.001 for both) and remained significantly lower at T2 in comparison to T0 (p = 0.009 and p = 0.01 respectively). Patients reported deficits in multiple domains of HR-QOL during recovery including global health status (p = 0.04), physical functioning (p < 0.001) and role functioning (p < 0.001). Role functioning remained a clinically important 33-points lower than pre-operative values at T2. CONCLUSION: Habitual physical activity participation remains significantly impaired at 6-months post-oesophagectomy. Physical activity is a measurable and modifiable target for physical rehabilitation, which is closely aligned with patient-reported deficits in role functioning. Rehabilitation aimed at optimising physical health in oesophageal cancer survivorship is warranted.

Effect of preoperative inspiratory muscle training on physical functioning following esophagectomy.

This study aims to examine the effect of preoperative inspiratory muscle training (IMT) on pre- and postoperative functional exercise performance in patients undergoing esophagectomy. A subcohort of patients recruited to the PREPARE randomized control trial were studied. Following evaluation of respiratory muscle function (spirometry, maximum inspiratory pressure (MIP), and inspiratory muscle endurance), postoperative mobilization (accelerometry) and postoperative physical functioning (6-minute walk test (6MWT)), participants scheduled for esophagectomy were randomly assigned to either 2 weeks of preoperative IMT or a control group. Measures were repeated on the day before surgery and postoperatively. Sixty participants (mean (standard deviation) age 64.13 (7.8) years; n = 42 male; n = 43 transthoracic esophagectomy; n = 17 transhiatial esophagectomy) were included in the final analysis (n = 28 IMT; n = 32 control). There was a significant improvement in preoperative MIP (P = 0.03) and inspiratory muscle endurance (P = 0.04); however preoperative 6MWT distance did not change. Postoperatively, control participants were more active on postoperative day (POD)1, and from POD1-POD5 (P = 0.04). Predischarge, 6MWT distance was significantly lower in the IMT group (305.61 (116.3) m) compared to controls (380.2 (47.1) m, P = 0.03). Despite an increase in preoperative respiratory muscle function, preoperative IMT does not improve pre- or postoperative physical functioning or postoperative mobilization following esophagectomy.

Diagnostic challenges in pyogenic spinal infection: an expanded role for FDG-PET/CT.

In a preliminary investigation of FDG-PET/CT for assessment of therapy response of pyogenic spine infection, it was concluded that activity confined to the margins of a destroyed or degenerated joint with bone-on-bone contact represents nonseptic inflammation, regardless of the intensity of uptake. Only activity in bone, soft tissue, or within the epidural space represents active infection. The purpose of this investigation was to assess the performance of these pattern-based interpretation criteria in a series of problem cases of proven or suspected spine infection. Eighty-two FDG-PET/CTs were done for initial diagnosis because other imaging failed to provide a definitive diagnosis and 147 FDG-PET/CTs were done to assess treatment responses. Pattern-based interpretations were compared with the clinical diagnosis based on bacterial cultures and outcomes after cessation or withholding of antibiotic therapy. Pattern-based interpretation criteria achieved a sensitivity and specificity of 98 and 100%, respectively, for initial diagnosis and a specificity of 100% for assessment of treatment response. The same data was analyzed using intensity of activity as the primary factor. Sensitivity and specificity using the intensity-based criteria were 93 and 68%, respectively, for initial diagnosis, and the specificity of a negative interpretation for therapy response was 55%. Differences from pattern-based criteria are highly significant. Pattern-based criteria perform well in problem cases with equivocal MR and for treatment response because they correctly eliminate activity from nonspecific inflammation associated with destroyed joints with bone-on-bone contact. Response occurs within a timeframe that is useful for managing antibiotic therapy.

Sarcopenia during neoadjuvant therapy for oesophageal cancer: characterising the impact on muscle strength and physical performance.

PURPOSE: Preoperative chemo(radio)therapy for oesophageal cancer (OC) may have an attritional impact on body composition and functional status, impacting postoperative outcome. Physical decline with skeletal muscle loss has not been previously characterised in OC and may be amenable to physical rehabilitation. This study characterises skeletal muscle mass and physical performance from diagnosis to post-neoadjuvant therapy in patients undergoing preoperative chemo(radio)therapy for OC. METHODS: Measures of body composition (axial computerised tomography), muscle strength (handgrip), functional capacity (walking distance), anthropometry (weight, height and waist circumference), physical activity, quality-of-life and nutritional status were captured prospectively. Sarcopenia status was defined as pre-sarcopenic (low muscle mass only), sarcopenic (low muscle mass and low muscle strength or function) or severely sarcopenic (low muscle mass and low muscle strength and low muscle function). RESULTS: Twenty-eight participants were studied at both time points (mean age 62.86 ± 8.18 years, n = 23 male). Lean body mass reduced by 4.9 (95% confidence interval 3.2 to 6.7) kg and mean grip strength reduced by 4.3 (2.5 to 6.1) kg from pre- to post-neoadjuvant therapy. Quality-of-life scores capturing gastrointestinal symptoms improved. Measures of anthropometry, walking distance, physical activity and nutritional status did not change. There was an increase in sarcopenic status from diagnosis (pre-sarcopenic n = 2) to post-treatment (pre-sarcopenic n = 5, severely sarcopenic n = 1). CONCLUSIONS: Despite maintenance of body weight, functional capacity and activity habits, participants experience declines in muscle mass and strength. Interventions involving exercise and/or nutritional support to build muscle mass and strength during preoperative therapy, even in patients who are functioning normally, are warranted.

Reduced fitness and physical functioning are long-term sequelae after curative treatment for esophageal cancer: a matched control study.

Reduced physical functioning is common following resections for esophageal cancer; however, objective data on physical performance outcomes in this cohort are rare. The aim of this study was to assess the physical performance and health related quality of life (HRQOL) of disease free survivors and compare findings in a case matched noncancer control group. Twenty-five males (mean (±SD) aged 63 (±6) years) who were over 6 months postesophagectomy and disease-free were compared with 25 controls (60 ± 6 years). Physical functioning was assessed through hand grip strength (dynamometry), exercise capacity (incremental shuttle walk test), physical activity levels (RT3 accelerometer), and body composition (bio-electrical impedance analysis). Health-related quality of life was measured using the EORTC QLQ-C30 questionnaire. Esophageal cancer survivors demonstrated significantly lower fitness (P < 0.001) and time spent in moderate (P < 0.001) and vigorous (P < 0.001) intensity physical activity compared with controls. Global health status and quality of life were similar in both groups (P = 0.245); however, physical and role functioning domains were lower in the cancer survivors (P < 0.001, and P = 0.001, respectively). These data show that disease-free survivors of curative esophageal cancer treatment demonstrate a significant compromise in physical functioning compared with controls, thus highlighting the multiple, complex rehabilitative needs of this cohort.

A Case of Primary Hyperparathyroidism Secondary to Parathyroid Adenoma in a Pediatric Patient.

Background/Objective: Although common in adults, primary hyperparathyroidism (PHPT) is a rare condition in children with the most common etiology being solitary parathyroid adenoma (PTA). The typical presentation is symptomatic hypercalcemia. Management of PHTP secondary to PTA requires excision of the adenoma. Case Report: A 13-year-old adolescent boy presented because of orbital cellulitis and was noted to have hypercalcemia. Despite this, the patient was curiously asymptomatic. Further investigations yielded an elevated parathyroid hormone (PTH) level and a normal urine calcium-to-creatinine ratio making the most likely cause of hypercalcemia PHTP secondary to PTA. Imaging demonstrated PTA. The patient underwent parathyroidectomy with the pathology demonstrating PTA. Postoperatively, the PTH levels were undetectable; hence, the patient was treated with calcitriol and calcium supplementation for 1 month and 4 months, respectively. Genetic work-up for multiple endocrine neoplasia 1 and rearranged during transfection mutations was negative. Discussion: Solitary PTA is the most common cause of PHPT. Adenomas are mostly sporadic or may be a manifestation of an inheritable syndrome, such as multiple endocrine neoplasia. Although symptomatic disease is more common in children, our patient denied any hypercalcemia symptoms. The distinguishing biochemical feature of PHPT because of PTA is high or inappropriately normal PTH level in the context of high-normal or elevated serum calcium levels. Urinary calcium excretion is usually normal or high. PTAs are localized by ultrasound and Tc-99m-Sestamibi scintigraphy. Management includes parathyroidectomy and monitoring for postoperative hypocalcemia. Conclusion: In a child or adolescent presenting with hypercalcemia and elevated PTH levels, it is important to consider PHPT secondary to PTA, because an early diagnosis will aid in preventing complications from hypercalcemia.

Shiga-toxigenic Escherichia coli from animal food sources in Mauritius: Prevalence, serogroup diversity and virulence profiles.

Shiga-toxigenic Escherichia coli (STEC) are important human pathogens associated with diarrhea and in some cases haemorrhagic colitis. Contaminated food derived from cattle and wildlife species are often associated with disease outbreaks. In this study, we report the prevalence, serogroup diversity and virulence profiles of STEC strains derived from cattle, rusa deer and pig. Of the 422 samples analyzed, STEC were detected in 40% (80/200) of cattle, 27.0% (33/122) of deer and 13.0% (13/100) of pigs. STEC isolates belonged to 38 O-serogroups whereby 5.2% (24/462) of the isolates belonged to clinically important EHEC-7 serogroups: O26 (n = 2), O103 (n = 1), O145 (n = 3) and O157 (n = 18). Fourteen serogroups (O26, O51, O84, O91, O100, O104, O110, O117, O145, O146, O156, O157, O177 and ONT) displayed multiple virulence profiles. We also identified two serovars (O117 and O119) in deer which are not well-documented in epidemiological surveys. 73.7% (28/38) of recovered O-serogroups are known to be associated with serious human illnesses including haemolytic uremic syndrome (HUS) and bloody diarrhea. STEC isolates harboring single genotypes stx1, stx2, eae and hlyA accounted for 3.0% (14/462), 9.1% (42/462), 47.6% (220/462) and 1.7% (8/462) of all STEC isolates screened, respectively. Virulence combinations stx1 and stx2 were harboured by 1.3% of isolates while strains with genetic profiles eae/hlyA were the second most prevalent amongst STEC isolates. The full known virulent genotypes (stx2/eae, stx1/stx2/eae, stx1/stx2/hlyA and stx2/eae/hlyA) were present in 22 of the 462 STEC strains. A total of 10 different virulence patterns were recovered amongst animal species. Phylogeny of the gnd gene showed that amongst STEC strains, serovar O100 outlined the main cluster. Fourteen (n = 14) different sequence types (STs) were identified from a panel of twenty (n = 20) STEC isolates. One of the isolate (PG007B) possessed a unique ST (adk 10, fumC 693, gyrB 4, icd 1, mdh 8, purA 8, recA 2) that could not be assigned using MLST databases. None of the ST's recovered in deer were observed in domestic species. Our findings shows that food associated animals found on the tropical island of Mauritius carry a diversity of STEC strains with many serovars known to be associated with human disease. This report indicates that increased awareness, surveillance and hygienic attention at critical stages of the human food chain are warranted.

Anaphase-promoting complex/cyclosome-dependent proteolysis of human cyclin A starts at the beginning of mitosis and is not subject to the spindle assembly checkpoint.

Cyclin A is a stable protein in S and G2 phases, but is destabilized when cells enter mitosis and is almost completely degraded before the metaphase to anaphase transition. Microinjection of antibodies against subunits of the anaphase-promoting complex/cyclosome (APC/C) or against human Cdc20 (fizzy) arrested cells at metaphase and stabilized both cyclins A and B1. Cyclin A was efficiently polyubiquitylated by Cdc20 or Cdh1-activated APC/C in vitro, but in contrast to cyclin B1, the proteolysis of cyclin A was not delayed by the spindle assembly checkpoint. The degradation of cyclin B1 was accelerated by inhibition of the spindle assembly checkpoint. These data suggest that the APC/C is activated as cells enter mitosis and immediately targets cyclin A for degradation, whereas the spindle assembly checkpoint delays the degradation of cyclin B1 until the metaphase to anaphase transition. The "destruction box" (D-box) of cyclin A is 10-20 residues longer than that of cyclin B. Overexpression of wild-type cyclin A delayed the metaphase to anaphase transition, whereas expression of cyclin A mutants lacking a D-box arrested cells in anaphase.

Long-term ecosystem monitoring and assessment of the Detroit River and Western Lake Erie.

Over 35 years of US and Canadian pollution prevention and control efforts have led to substantial improvements in environmental quality of the Detroit River and western Lake Erie. However, the available information also shows that much remains to be done. Improvements in environmental quality have resulted in significant ecological recovery, including increasing populations of bald eagles (Haliaeetus leucocephalus), peregrine falcons (Falco columbarius), lake sturgeon (Acipenser fulvescens), lake whitefish (Coregonus clupeaformis), walleye (Sander vitreus), and burrowing mayflies (Hexagenia spp.). Although this recovery is remarkable, many challenges remain, including population growth, transportation expansion, and land use changes; nonpoint source pollution; toxic substances contamination; habitat loss and degradation; introduction of exotic species; and greenhouse gases and global warming. Research/monitoring must be sustained for effective management. Priority research and monitoring needs include: demonstrating and quantifying cause-effect relationships; establishing quantitative endpoints and desired future states; determining cumulative impacts and how indicators relate; improving modeling and prediction; prioritizing geographic areas for protection and restoration; and fostering long-term monitoring for adaptive management. Key management agencies, universities, and environmental and conservation organizations should pool resources and undertake comprehensive and integrative assessments of the health of the Detroit River and western Lake Erie at least every 5 years to practice adaptive management for long-term sustainability.

Functional interaction between DP-1 and p53.

The cellular transcription factor DRTF1/E2F and the tumor suppressor protein p53 play important roles in controlling early cell cycle events. DRTF1/E2F is believed to coordinate and integrate the transcription of cell cycle-regulating genes, for example, those involved in DNA synthesis, with the activity of regulatory proteins, such as the retinoblastoma tumor suppressor gene product (pRb), which modulate its transcriptional activity. In contrast, p53 is thought to monitor the integrity of chromosomal DNA and when appropriate interfere with cell cycle progression, for example, in response to DNA damage. Generic DRTF1/E2F DNA binding activity and transcriptional activation arise when members of two distinct families of proteins, such as DP-1 and E2F-1, interact as DP/E2F heterodimers. In many cell types, DP-1 is a widespread component of DRTF1/E2F DNA binding activity which when expressed at high levels oncogenically transforms embryonic fibroblasts. Here, we document an association between DP-1 and p53 and demonstrate its presence in mammalian cell extracts. In vitro p53 interacts with an immunochemically distinct form of DP-1 and in vivo can regulate transcription driven by the DP-1/E2F-1 heterodimer. At the biochemical level, p53 competes with E2F-1 for DP-1, with a consequent reduction in DNA binding activity. Mutational analysis defines within DP-1 a C-terminal region required for the interaction with p53 and within p53 an N-terminal region distinct from that required to bind to MDM2. Our results establish DRTF1/E2F as a common cellular target in growth control mediated through the activities of pRb and p53 and suggest an alternative mechanism through which p53 may regulate cellular proliferation.

Identification of the domains in cyclin A required for binding to, and activation of, p34cdc2 and p32cdk2 protein kinase subunits.

The binding of cyclin A to p34cdc2 and p32cdk2 and the protein kinase activity of the complexes has been measured by cell-free translation of the corresponding mRNA in extracts of frog eggs, followed by immunoprecipitation. A variety of mutant cyclin A molecules have been constructed and tested in this assay. Small deletions and point mutations of highly conserved residues in the 100-residue "cyclin box" abolish binding and activation of both p34cdc2 and p32cdk2. By contrast, large deletions at the N-terminus have no effect on kinase binding and activation, until they remove residues beyond 161, where the first conserved amino acids are found in all known examples of cyclin A. At the C-terminus, removal of 14 or more amino acids abolishes activity. We also demonstrate that deletion of, or point mutations, in the cyclin A homologue of the 10-residue "destruction box," previously described in cyclin B (Glotzer et al., 1991) abolish cyclin proteolysis at the transition from M-phase to interphase.

Isotretinoin administration improves sperm production in men with infertility from oligoasthenozoospermia: a pilot study.

There is currently no effective medical therapy for men with infertility due to oligoasthenozoospermia. As men with abnormal sperm production have lower concentrations of 13-cis-retinoic acid in their testes, we hypothesized that men with infertility from oligoasthenozoospermia might have improved sperm counts when treated with isotretinoin (13-cis-retinoic acid). We conducted a single-site, single-arm, pilot study to determine the effect of therapy with isotretinoin on sperm indices in 19 infertile men with oligoasthenozoospermia. Subjects were men between 21 and 60 years of age with infertility for longer than 12 months associated with sperm concentrations below 15 million sperm/mL. All men received isotretinoin 20 mg by mouth twice daily for 20 weeks. Subjects had semen analyses, physical examinations, and laboratory tests every 4 weeks during treatment. Nineteen men enrolled in the study. Median (25th, 75th) sperm concentration increased from 2.5 (0.1, 5.9) million/mL at baseline to 3.8 (2.1, 13.0) million/mL at the end of treatment (p = 0.006). No significant changes in sperm motility were observed. There was a trend toward improved sperm morphology (p = 0.056). Six pregnancies (three spontaneous and three from intracytoplasmic sperm injection) and five births occurred during the study. Four of the births, including all three of the spontaneous pregnancies, were observed in men with improvements in sperm counts with isotretinoin therapy. Treatment was well tolerated. Isotretinoin therapy improves sperm production in some men with oligoasthenozoospermia. Additional studies of isotretinoin in men with infertility from oligoasthenozoospermia are warranted.

Effects of in vitro electrical stimulation on enhancement and suppression of malignant lymphoma cell proliferation.

The suppression and enhancement of proliferation of mouse EL4 lymphoma cells varied significantly when the cells were electrically stimulated within a narrow range of low-level direct current. With the use of platinum electrodes, the suppression characteristics were observed over a narrow range, or window, of direct currents centered at approximately 17 microA. Enhancement characteristics were observed over a broad range of low-level direct currents (approximately 0.1 to 10 microA). These results indicate that the proliferation of certain eukaryotic cells may be directly controlled by stimulation with low-level direct current.

New ASCO/CAP guideline recommendations for HER2 testing increase the proportion of reflex in situ hybridization tests and of HER2 positive breast cancers.

Accurate determination of tumour human epidermal growth factor receptor type 2 (HER2) status is critical for optimal treatment of breast cancer. In October 2013, the American Society of Clinical Oncology (ASCO) and the College of American Pathologists (CAP) issued joint updated guideline recommendations for HER2 testing in breast cancer, with a revised algorithm for interpretation of immunohistochemistry (IHC) and in situ hybridisation (ISH) results. This study investigates the impact on HER2 IHC categorisation, implication for reflex ISH testing and potential for identification of false negative IHC. HER2 IHC preparations on 251 invasive breast tumours, originally reported according to 2007 guidelines, were re-scored using 2013 guidelines and the diagnostic categories compared. The results of ISH testing on a separate cohort of 32 breast tumours reported as HER2 IHC 2+ following the introduction of the 2013 guidelines, that would have been designated 1+ according to 2007, were reviewed. Application of 2013 guidelines resulted in a decrease in tumours classified as HER2 negative (83/251 vs 144/251) and a comparable increase in those classified as equivocal (2+) (139/251 vs 80/251). Relatively few tumours were re-classified as positive (29/251 vs 27/251). Furthermore, 3/32 breast cancer cases (HER2 IHC 2+ as per 2013 guidelines, 1+ using 2007 guidelines) were HER2 ISH positive. Application of the 2013 guidelines increases the HER2 IHC equivocal (2+) category and requirement for reflex ISH testing. The reduced threshold for ISH testing identifies some patients with HER2 positive breast cancer whose tumours would have been categorised as HER2 negative according to the 2007 guidelines.

The use of three-dimensional strut plates for the management of mandibular angle fractures: a retrospective analysis of 222 patients.

This study was performed to evaluate the use of three-dimensional (3D) strut plates for the surgical management of mandibular angle fractures and to determine the subsequent postoperative complication rate. Two hundred and twenty-two patients met the inclusion criteria for mandible angle fracture at the university hospital in Miami between 2009 and 2013 and were included in this study. The treatment protocol for mandibular angle fractures included open reduction and internal fixation with the utilization of a 3D strut plate. Patients were not placed in postoperative intermaxillary fixation. An evaluation of the cases revealed a complication rate of 15.3%, of which 6.8% were considered major complications requiring a surgical intervention. The 3D strut plate has been found to have many advantages over single miniplate techniques with respect to the stability of the fracture and the rate of complications. Based on the current data, 3D strut plates provide a predictable result in the treatment of mandibular angle fractures.

Genetic and immunochemical analysis of mutant p53 in human breast cancer cell lines.

The expression of the tumour suppressor gene p53 was analysed in 11 human breast cancer cell lines by immunohistochemistry, immunoprecipitation and cDNA sequencing. We used a panel of anti-p53 monoclonal antibodies for cell staining and found abnormalities in every case. Eight of the cell lines produce a form of p53 which can be immunoprecipitated by the monoclonal antibody PAb240 but not by PAb1620. In the murine system PAb240 only immunoprecipitates mutant p53. We sequenced p53 cDNA directly from four of the PAb240 positive cell lines using asymmetric PCR templates. All four contained missense mutations in p53 RNA, with no detectable expression of the wild type sequence. Different residues were affected in each cell line, but all the mutations changed amino acids conserved from man to Xenopus. These results imply that as in the murine system, the PAb240 antibody reliably detects a wide variety of p53 mutations and that these mutations have a common effect on the structure of p53. Immunohistochemical data suggest that p53 mutation is the commonest genetic alteration so far detected in primary breast cancer.

Loss of heterozygosity and mutational alterations of the p53 gene in skin tumours of interspecific hybrid mice.

Functional alterations or loss of tumor-suppressor genes are an important feature of neoplastic progression in humans. The employment of suitable animal model systems would greatly facilitate the detection and manipulation of such genes. We describe here an experimental approach to this problem based on the analysis of skin tumors induced in F1 hybrids between Mus musculus and Mus spretus mice. The results show that loss of heterozygosity on chromosome 11 occurred in 4/13 mouse skin carcinomas, but not in premalignant papillomas. Since the murine p53 gene is located on this chromosome, immunoprecipitation and DNA-sequencing studies were carried out on tumorigenic cell lines and primary tumor DNA respectively to determine the status of p53 alleles. These studies revealed the presence of p53 mutations, both frameshifts and missense, some of which are identical to those found in human tumors. Loss of normal p53 function is found in well-differentiated squamous-cell carcinomas and thus does not appear to be directly responsible for further progression to an undifferentiated spindle cell phenotype.

Aberrant expression of the p53 oncoprotein is a common feature of a wide spectrum of human malignancies.

Accumulation of the p53 protein was analysed in 212 human malignant lesions. Immunohistochemical staining with new polyclonal (CM-1) and monoclonal antibodies (BP 53-12 and BP53-24) to p53 on methacarn-fixed paraffin sections showed positive staining in 161 (76%). The positive tumours were found across a wide range of human malignancies including breast, colon, stomach, bladder and testis carcinomas, soft-tissue sarcomas and melanomas. The staining was always confined to the malignant lesion. Immunoprecipitation and quantitative ELISA assays established that the positive staining was associated with accumulation of the protein and that the protein was frequently in a mutant conformation. Accumulation of mutant p53 protein is therefore a common feature of human malignant disease.