Abstract 1093: p16 promotes Rb deficient pulmonary epithelial progenitor cell growth

The retinoblastoma (Rb)/p16 pathway is deregulated in virtually all lung cancers, providing evidence that Rb and p16 are essential regulators in the lung epithelium. Although Rb is critical for suppressing epithelial proliferation and death during lung development, progenitor cells compensate for Rb loss after birth. Previous studies demonstrate that this compensation is associated with increased p16 expression. The purpose of this study was to 1) determine whether p16 repression in vivo was unique to Rb or represented a shared pocket protein function and 2) test the hypothesis that p16 has Rb-independent functions critical for controlling pulmonary epithelial progenitor cell growth. p16 was induced in Rb deficient lungs wherein Rb ablation was targeted to the lung epithelium using the Cre/LoxP system. In contrast, p16 expression was not induced in lungs from p107−/− or p130−/− mice. Despite robust p16 expression, Rb deficient lungs did not undergo senescence as assessed by senescence associated β-galactosidase activity. To determine the effects of altered Rb/p16 pathway function on epithelial progenitor cell growth, primary type II cell cultures were established from Rb ablated, combined Rb ablated/p16−/−, and control Rb/p16 proficient lungs. Rb loss resulted in increased cell growth over controls. Interestingly, combined Rb/p16 loss resulted in decreased growth as compared to Rb ablation alone, indicating that p16 enhances Rb deficient pulmonary progenitor cell growth. Flow cytometric analysis and BrdU labeling revealed that loss of Rb led to increased cell survival and that additional loss of p16 decreased cell growth by promoting cell death and suppressing proliferation. Taken together, these data demonstrate that p16 induction in Rb deficient pulmonary progenitor cells does not lead to senescence but rather enhances cell growth by promoting cell survival and proliferation. These studies identify fundamental differences between Rb/p16 pathway regulation of pulmonary epithelial progenitor cells and previously described functions in fibroblasts: 1) p16 repression is an Rb unique function in the lung in vivo, whereas all three Rb family proteins repress p16 in fibroblasts and 2) Rb and Rb/p16 loss have profound effects on epithelial progenitor cell growth, whereas growth of Rb−/− and p16−/− murine embryo fibroblasts is similar to wild type controls. The current data provide evidence that p16 enhances survival and proliferation of Rb deficient epithelial progenitor cells, thus identifying a novel Rb-independent p16 function. Greater than 80% of human adult malignancies are epithelial derived carcinomas. Therefore, identifying cell type specific Rb/p16 pathway functions critical for controlling epithelial cell growth is a vital step toward understanding cancer pathogenesis.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1093.

Retinoblastoma family proteins have distinct functions in pulmonary epithelial cells in vivo critical for suppressing cell growth and tumorigenesis

Lung cancer is the leading cause of cancer deaths, accounting for more deaths than breast, colon, and prostate cancer combined. The retinoblastoma (Rb)/p16 tumor suppressive pathway is deregulated in most cancers. Loss of p16 occurs more frequently than Rb loss, suggesting that p16 suppresses cancer by regulating Rb as well as the related proteins p107 and p130. However, direct evidence demonstrating that p130 or p107 cooperate with Rb to suppress epithelial cancers associated with p16 loss is currently lacking. Moreover, the roles of p130 and p107 in lung cancer are not clear. In the present studies, Rb ablation was targeted to the lung epithelium in wild-type, p107, or p130 null mice to determine unique and overlapping Rb family functions critical in tumor suppression. Rb ablation during development resulted in marked epithelial abnormalities despite p107 upregulation. In contrast, p130 and p107 were not required during development but had distinct functions in the Rb-deficient epithelium: p107 was required to suppress proliferation, whereas a novel proapoptotic function was identified for p130. Adult Rb-ablated lungs lacked the epithelial phenotype seen at birth and showed compensatory p107 upregulation and p16 induction in epithelial cell lineages that share phenotypic characteristics with human non-small cell lung cancers (NSCLC) that frequently show p16 loss. Importantly, Rb/p107-deficient, but not Rb/p130-deficient, lungs developed tumors resembling NSCLC. Taken together, these studies identify distinct Rb family functions critical in controlling epithelial cell growth, and provide direct evidence that p107 cooperates with Rb to protect against a common adult cancer.

Overexpression of the cellular DEK protein promotes epithelial transformation in vitro and in vivo

High levels of expression of the human DEK gene have been correlated with numerous human malignancies. Intracellular DEK functions have been described in vitro and include DNA supercoiling, DNA replication, RNA splicing, and transcription. We have shown that DEK also suppresses cellular senescence, apoptosis, and differentiation, thus promoting cell growth and survival in monolayer and organotypic epithelial raft models. Such functions are likely to contribute to cancer, but direct evidence to implicate DEK as an oncogene has remained elusive. Here, we show that in line with an early role in tumorigenesis, murine papilloma formation in a classical chemical carcinogenesis model was reduced in DEK knockout mice. Additionally, human papillomavirus E6/E7, hRas, and DEK cooperated in the transformation of keratinocytes in soft agar and xenograft establishment, thus also implicating DEK in tumor promotion at later stages. Finally, adenoviral DEK depletion via short hairpin RNA expression resulted in cell death in human tumor cells in vitro and in vivo, but did not significantly affect differentiated epithelial cells. Taken together, our data uncover oncogenic DEK activities as postulated from its frequent up-regulation in human malignancies, and suggest that the targeted suppression of DEK may become a strategic approach to the treatment of cancer.

Evaluating a spoken dialogue system for recording clinical observations during an endoscopic examination

Paper, keyboard or mouse-driven systems may not be suitable for data capture because of the hands-busy constraint imposed by an endoscopic examination. A Spoken Dialogue System (SDS) has a number of advantages when compared to keyboard and mouse-driven input modalities, particularly with respect to hands free and eyes-free control of a system. However, any emerging technology will never deliver improved organizational effectiveness if it is not accepted and used. The Technology Acceptance Model (TAM) provides a framework that helps explain the determinants of computer acceptance. This study, through the application of TAM, demonstrates a high level of user acceptance with clinicians wanting to use spoken dialogue technology for recording clinical observations during an endoscopic examination. Clinicians would also prefer to use a SDS for recording endoscopy rather than use a paper-based or keyboard and mouse-driven system. Using a clinical narrative during an endoscopic examination was also perceived to be a natural way to record findings. Relationships between basic TAM variables were confirmed and relationships between quality of dialogue measures and TAM variables were established.

Changing patterns of postural hip muscle activity during recovery from stroke

OBJECTIVE

To describe the recovery of neurophysiological responses to perturbation of standing balance after stroke.

METHODS

Surface electromyography (EMG) from hip abductors and adductors and ground reaction forces (GRF) were measured in response to 20 sideways pushes applied to the pelvis by a linear motor. Each subject's data from pushes in each direction were averaged and the presence of a muscle EMG response was assessed visually.

SUBJECTS

Thirteen acute hemiplegic patients were tested as soon as they could stand after stroke (median six weeks) and serially during recovery.

RESULTS

Four patterns of hip muscle activity were seen: (1) no response at all, (2) no response in hemiparetic muscles but compensation by contralateral muscles, (3) an appropriate, if delayed, response in the hemiparetic abductor but not adductor muscles, and (4) a relatively normal pattern in both hemiparetic muscles. Nine of 13 patients showed a change in pattern of hip muscle activity during recovery. All patients who initially resisted the sideways pushes solely with muscles of the unaffected leg later regained use of the hemiparetic hip abductors.

CONCLUSIONS

The pattern of hip muscle activation changed towards normal during recovery from stroke in most patients. Use of compensatory strategies early after stroke in these subjects did not prevent return of normal patterns of muscle activation later.

Stepping before standing: hip muscle function in stepping and standing balance after stroke

OBJECTIVE

To compare the pattern of pelvic girdle muscle activation in normal subjects and hemiparetic patients while stepping and maintaining standing balance.

DESIGN

Group comparison.

METHOD

Seventeen patients who had regained the ability to walk after a single hemiparetic stroke were studied together with 16 normal controls. Median interval between stroke and testing was 17 months. Amplitude and onset latency of surface EMG activity in hip abductors and adductors were recorded in response to sideways pushes in either direction while standing. Similar recordings were made in the same subjects during gait initiation and a single stride.

RESULTS

In the standing balance task, normal subjects resisted a sideways push to the left with the left gluteus medius (74 ms) and with the right adductor (111 ms), and vice versa. In hemiparetic patients, the amplitude of activity was reduced in the hemiparetic muscles, the onset latencies of which were delayed (gluteus medius 96 ms, adductor 144 ms). Contralateral, non-paretic, adductor activity was increased after a push towards the hemiparetic side of patients with stroke and the latency was normal (110 ms). During self initiated sideways weight shifts at gait initiation, hemiplegic muscle activation was impaired. By contrast, the pattern and peak amplitude of hip muscle activation in stepping was normal in both hemiparetic and non-hemiparetic muscles of the subjects with stroke.

CONCLUSIONS

In ambulant patients with stroke, a normal pattern of activation of hemiparetic muscles is seen in stepping whereas the response of these muscles to a perturbation while standing remains grossly impaired and is compensated by increased activity of the contralateral muscles. This suggests that hemiparetic patients should be able to step before regaining standing balance.

Surgical treatment of gastric leiomyoma in a dog

A 12-year-old entire male Maltese terrier was presented with a 1 month history of vomiting and haematemesis. Microcytic hypochromic anaemia was detected. Abdominal radiography, ultrasonography and gastric endoscopy identified a discrete intramural mass in the pyloric antrum. An ulcerated leiomyoma was removed by a partial-thickness intraluminal resection of the gastric wall. The dog recovered well and is free from clinical signs 20 months after surgery.

A suggested methodology for the construction of national bone densitometry reference ranges: 1372 Caucasian women from four UK sites

This paper presents a simple methodology for combining bone densitometry data from different sites in the UK, having instruments from the same manufacturer (LUNAR Radiation). Additive normalization factors were used on all data prior to inclusion in a reference database which ultimately included data on 1372 Caucasian women, aged 20-70 years, of whom 749 were post-menopausal. Reference data for spine (L2-L4) and femoral neck bone mineral density are given in tabular form as 3 year moving averages for: (1) all women; (2) perimenopausal women grouped by menopausal status; and (3) post-menopausal women with respect to years since menopause. These data may be used to construct Z-score. T-score or percentile reporting ranges and may be adopted as the core for a UK reference range.

An open access bone densitometry service: report of first year's operation

Medical treatment of symptomatic osteoporosis is unsatisfactory. Treatment of patients with low bone density but without history of fracture includes hormone replacement therapy (HRT) which offers the prospect of reduced fracture risk. Dual energy X-ray absorptiometry (DXA) offers a safe and accurate technique available for the measurement of bone mineral density at a district general hospital level. All open access service providing densitometry measurements for general practitioners and hospital consultants was instigated at South Cleveland Hospital in February 1991. A major purpose of the service was to provide density measurements in order to 'inform' the discussion between the patient and doctor with regard to the use of anti-resorptive and other medical agents. We report our experience of operating such a service. The report analyses the main reasons for referrals. Nine hundred and thirty female subjects and 63 male subjects were scanned. The main reason for female referral were early menopause, consideration for HRT, personal history of fracture and family history of fracture--these account for 54.7% of all referrals. In men, there was a high incidence of fracture, back pain and the use of steroids given as reasons for referral. Sixty-seven per cent of patients were referred by general practitioners. Eighteen per cent of female lumbar spinal BMD values were between 1 and 2 S.D. below the Leeds normative mean and 9.0% below 2 S.D. Figures for the femoral neck were 22.0 and 9.0%.(ABSTRACT TRUNCATED AT 250 WORDS)

A computer designed graph for administration of atracurium by i.v. infusion

A bi-exponential mathematical computer model was used to develop a guidance graph for atracurium infusions. The model permitted variation in infusion rates, in pharmacokinetic parameters and in "effect" thresholds. Systematic experiments revealed a relationship between the rate of recovery from a fixed bolus loading dose and the most appropriate initial infusion rate. This relationship was expressed as a guidance graph or "ready reckoner". The quality of guidance was assessed in 50 anaesthetics, given consecutively. In 39 patients optimal myoneural block for surgery was maintained for the duration of the infusion without adjustments or supplementary bolus doses. The mean operating time was 92 min and the mean duration of infusion was 59 min.

Vecuronium bromide in anaesthesia for laparoscopic sterilization

Vecuronium bromide 70 micrograms kg-1 was used to facilitate tracheal intubation and provide neuromuscular blockade in 52 patients undergoing laparoscopic sterilization. Anaesthesia was maintained with 67% nitrous oxide in oxygen. Patients were monitored clinically and by tactile assessment of the evoked response of the adductor pollicis to a supramaximal train-of-four stimulation. Intubating conditions were assessed at 90 s in the first 33 patients, and were poor. They improved significantly in the subsequent 19 patients when intubation was delayed until 150 s (P less than 0.05). Operating conditions were good in all except two patients. Residual neuromuscular blockade was antagonized rapidly at completion of surgery by neostigmine 2.5 mg i.v., which was administered provided there was at least one twitch response. The mean duration of the procedure was 14.3 min (SD 2.5 min). The mean time from injection of neostigmine to satisfactory spontaneous breathing and neuromuscular recovery was 1.6 min (SD 0.7 min).

The ureases of Proteus strains in relation to virulence for the urinary tract

The ureases produced by a large number of strains of different Proteus species, some of which were known to have a special affinity for the urinary tract, were examined by polyacrylamide-gel electrophoresis. Each Proteus strain gave a pattern of urease isoenzymes that was characteristic and unique to its species although strains of P. Mirabilis and P. vulgaris gave isoenzyme patterns that were closely similar. There was some minor variation in the patterns of urease isoenzymes even between strains of the same species. This was most noticeable among P. rettgeri strains and to a lesser extent among P. vulgaris strains. No correlation was found between the types of ureases a strain produced and its pathogenicity for the urinary tract.

Mobile resuscitation. A review of 200 calls attended by anaesthetists

Evaluation of practice in a mobile resuscitation unit, staffed routinely by anaesthetists, over a 3 month period is described. Of 200 calls attended, the doctor was considered to have played a necessary role in sixty-seven, and in seven patients the doctor's attendance was considered to have contributed significantly to the patient's survival.