On reducing hand impact force in forward falls: results of a brief intervention in young males

OBJECTIVE

To test the working hypotheses that after a brief (10 min) intervention, (a) young adults can volitionally reduce fall-related wrist impact forces, and (b) no difference in impact force would exist between intervention and control groups at 3-weeks or 3-months follow-up.

BACKGROUND

The wrist is the most commonly fractured site in the body at any age, most often as a result of impact with the ground while arresting a forward fall.Methods. Twenty-nine healthy young male volunteers participated. A 3-month intervention group (n=10) performed five standardized forward falls before and after a 10-min instructional intervention aimed at reducing wrist impact forces during the baseline visit. They, along with a 3-month control group (n=11) who did not receive the intervention, were remeasured in five trials at 3-weeks and 3-months follow-up, without intervening practice. A baseline control group (n=8) performed the five trials, then repeated them at the baseline visit without receiving the intervention. Unilateral body segment kinematics and bilateral hand-ground impact forces were measured and the hypotheses were tested using repeated measures analysis of variance.

RESULTS

At the baseline visit, a significant group-by-trial-block interaction was found (P=0.02): the 3-month intervention group reduced their average maximum impact forces by 18% from initial values (P=0.002); the baseline control group did not do so (0.5% increase, P=0.91). The 3-month intervention (20 falls) and control (15 falls) groups did not differ at the 3-month follow-up (P=0.62); however, when the groups were combined their maximum impact force had decreased significantly (8.9%, P=0.04) over that time.

CONCLUSIONS

Healthy young males learned in 10 min to significantly reduce wrist impact forces in forward falls, but retention was poor at 3-weeks follow-up. Irrespective of group, however, after the 5 falls at 3-weeks subjects had taught themselves to reduce their impact forces at the 3-months follow-up.

RELEVANCE

A brief educational intervention can significantly reduce forward fall-related impact forces in the short term. However, with or without the brief intervention, the experience of performing between 5-10 forward falls 3 weeks apart apparently resulted in decreased impact forces over the next 2 months, thereby reducing the risk of injury in these forward falls.

Prone table stereotactic breast biopsy

The prone table machine is a mammographic X-ray system specially designed for use in the stereotactic localisation of breast abnormality. In this study, its clinical usefulness was investigated in terms of duration, success rate, complications, and patients' acceptance of the procedure. During a 5-month period, 79 patients attended the Kwong Wah Hospital for stereotactic-guided biopsy on the prone table. Eighty-one lesions were assessed-seven by fine needle aspirations, 67 by large-core needle biopsies, and seven by vacuum-assisted biopsies. Most of the biopsies were done because of clustered microcalcifications (77.8%) and the majority were of mammographically indeterminate nature (58.0%). The mean duration of the procedure was 49 minutes. A high degree of acceptance was experienced by patients. Only one patient had persistent haemorrhage after the biopsy. In conclusion, the prone table machine was considered to be useful and efficient, and had a high degree of acceptance among patients.

High-pressure gel loader for capillary array electrophoresis microchannel plates

Microfabricated capillary array electrophoresis (microCAE) microchannel plates are the next generation of bioanalytical separation devices. To fully exploit the capabilities of microCAE devices, supporting technology such as robotic sample loading, gel loading, microplate washing, and data analysis must be developed. Here, we describe a device for loading gel into radial capillary array electrophoresis microplates and for plate washing and drying. The microplates are locked into a loading module, and high-pressure helium is used to drive aqueous separation media or wash solutions into the microchannels through fixtures connected to the central anode reservoir. Microplates are rapidly (30 s to 5 min) loaded with separation media, such as 3%-4.8% linear polyacrylamide or 0.7%-3.0% hydroxyethyl cellulose, for electrophoresis. The effective and rapid gel-filling and plate-cleaning methods together with short electrophoretic analysis times (2-30 min) make microCAE systems versatile and powerful nucleic acid analysis platforms.

Acute anorectic effect of single and combined drugs in mice using a non-deprivation protocol

RATIONALE

Studies of the effect of anorectic drugs such as fenfluramine in mice have indicated the desirability of using experimental protocols that do not involve deprivation.

OBJECTIVE

We have developed a non-deprivation or "dessert" protocol for use in mice that are maintained in standard housing conditions, and examine the effects of a serotonergic agent dexfenfluramine (DFEN), a dopaminergic agent phentermine (PHEN), and a selective norepinephrine uptake inhibitor thionisoxetine (TNIX) alone and in combination.

METHODS

Female C57BL/6J mice were adapted to 30 min daily presentation of a gelatinized form of sweetened milk using a holder that hooks over the side of the cage during tests; food spillage and contamination are minimal. Dose-inhibition curves were determined for DFEN, PHEN, and TNIX alone and for fixed ratio combinations of DFEN with either PHEN or TNIX.

RESULTS

Each drug produced a near linear dose-inhibition curve with the 50% inhibitory doses (DI50) of 5.6, 3.2 and 12.2 mg/kg, respectively. By isobolographic analysis, the effects of the drug combinations were strictly additive.

CONCLUSION

The procedure described is highly suitable for testing anorectic drugs in mice and is adaptable to a variety of housing conditions and diets. The DFEN+ PHEN combination was additive, which contrasts with its reported supra-additive effect in rats.

Altered matrix metalloproteinase expression associated with oncogene-mediated cellular transformation and metastasis formation

Matrix metalloproteinase expression was examined in a series of mammalian cell lines of varying degrees of malignant progression. The expression of MMP-2 and MMP-9 was found to correlate with ras-mediated cellular transformation and as a function of malignant potential. Altered MMP-2 and MMP-9 expression was found to correlate also in other oncogene transformed cell lines and the level of expression of both MMP-2 and MMP-9 correlated with metastatic potential. Increased expression of both MMP-2 and MMP-9 was also found in cells which constitutively over-express MAP kinase kinase suggesting that one of the consequences of the persistent activation of the MAP kinase pathway is elevated expression of MMP-2 and MMP-9. Additionally, this study demonstrated a correlation between the expression of MMP-3 (stromelysin-1) and the level of ras expressed in cells and with the cells' ability to form tumors and with malignant potential. The existence of a novel 80 kDa caseinase activity which correlates with ras expression and the ability of the cell to form tumors was also demonstrated. The growth status of transformed cells was also found to be important in determining the expression of MMP-2 mRNA but not MMP-9 mRNA expression, and this expression was cell-type specific. This study also demonstrates that oncogenes can interact to influence and to determine the nature of the matrix metalloproteinases expressed and that this interaction results in a tumorigenic phenotype and, most importantly, contributes to the metastatic phenotype. Alterations in the expression and the regulation of MMPs, particularly MMP-2 and MMP-9, constitute an integral part of the altered growth regulatory program found within transformed cells and in particular, in transformed cells capable of malignant progression.

Functional domains of the ClpA and ClpX molecular chaperones identified by limited proteolysis and deletion analysis

Escherichia coli ClpA and ClpX are ATP-dependent protein unfoldases that each interact with the protease, ClpP, to promote specific protein degradation. We have used limited proteolysis and deletion analysis to probe the conformations of ClpA and ClpX and their interactions with ClpP and substrates. ATP gamma S binding stabilized ClpA and ClpX such that that cleavage by lysylendopeptidase C occurred at only two sites. Both proteins were cleaved within in a loop preceding an alpha-helix-rich C-terminal domain. Although the loop varies in size and composition in Clp ATPases, cleavage occurred within and around a conserved triad, IG(F/L). Binding of ClpP blocked this cleavage, and prior cleavage at this site rendered both ClpA and ClpX defective in binding and activating ClpP, suggesting that this site is involved in interactions with ClpP. ClpA was also cut at a site near the junction of the two ATPase domains, whereas the second cleavage site in ClpX lay between its N-terminal and ATPase domains. ClpP did not block cleavage at these other sites. The N-terminal domain of ClpX dissociated upon cleavage, and the remaining ClpXDeltaN remained as a hexamer, associated with ClpP, and expressed ATPase, chaperone, and proteolytic activity. A truncated mutant of ClpA lacking its N-terminal 153 amino acids also formed a hexamer, associated with ClpP, and expressed these activities. We propose that the N-terminal domains of ClpX and ClpA lie on the outside ring surface of the holoenzyme complexes where they contribute to substrate binding or perform a gating function affecting substrate access to other binding sites and that a loop on the opposite face of the ATPase rings stabilizes interactions with ClpP and is involved in promoting ClpP proteolytic activity.

Cross tolerance between anorectic action and induction of Fos-ir with dexfenfluramine and 5HT1B/2C agonists in rats

RATIONALE

We have shown that the anorectic effect of dexfenfluramine (DFEN), an agent that acutely increases synaptic availability of serotonin (5-HT), shows complete tolerance after 2-3 prior applications when using acute feeding protocols and low dosages. It is unlikely this is due to either accumulative weight loss or presynaptic 5-HT depletion. In this study, we examined the possible contribution of 5-HT1B/2C receptors to behavioral tolerance by testing for cross tolerance between DFEN and the 5-HT1B/2C receptor agonists, m-chloro- and trifluoromethyl-substituted phenylpiperazines (mCPP and TFMPP). Additionally, we sought neuronal correlates of the behavioral changes by study of the induction of Fos-like immunoreactivity (ir) in discrete brain regions.

METHODS

Sprague-Dawley rats received two or three pre-injections, at 2-day intervals, of 2 mg/kg DFEN or vehicle. The rats were then food deprived for 24 h and, 30 min prior to a 1-h feeding test, received a s.c. injection of either DFEN, TFMPP (1 mg/kg), or mCPP (2 mg/kg). Additional groups received mCPP preinjections and test injection of either DFEN or mCPP. Rats in Fos-ir studies received similar injection regimens but were not food deprived and were perfused 1.5 h after the test injection.

RESULTS

DFEN-pretreated rats showed complete anorectic tolerance to DFEN, TFMPP, and mCPP. However, rats given this regimen of mCPP pretreatment were tolerant to neither mCPP nor DFEN. Fos-ir induced by DFEN in each brain region examined was either significantly reduced or abolished by prior DFEN injections. TFMPP induced less Fos-ir in these regions than DFEN and this was attenuated by prior DFEN.

CONCLUSIONS

The behavioral data indicate that tolerance to DFEN anorexia is mediated partially or completely by functional subsensitivity at 5-HT1B and/or 5-HT2C receptors. The brain regions implicated include the paraventricular hypothalamus, medial striatum, lateral parabrachial nucleus, and nucleus of the solitary tract.

Transforming growth factor beta1 selectively regulates ferritin gene expression in malignant H-ras-transformed fibrosarcoma cell lines

Transforming growth factor beta1 is an important growth regulator in many cell types, usually exerting a negative effect on cellular growth. Inhibition of DNA synthesis and cell proliferation is frequently lost during malignant transformation, and in some cases, tumor cell proliferation is actually stimulated by TGF-beta1. The present study demonstrates a novel link between alterations in TGF-beta1 regulation during malignant conversion, and the expression of ferritin, an important activity involved in a number of biological functions including iron homeostasis and cell-growth control. A series of H-ras-transformed mouse 10 T 1/2 cell lines, exhibiting increasing malignant potential, was investigated for possible TGF-beta1-mediated changes in ferritin gene expression. Selective induction of gene expression was observed, since only H-ras-transformed cells with malignant potential exhibited marked elevations in ferritin gene expression, in particular, alterations in H-ferritin gene expression. The regulation of H-ferritin gene expression in response to TGF-beta1 did not involve alterations in transcription, but occurred through mechanisms of post-transcriptional stabilization of the H-ferritin mRNA. Additionally, evidence was obtained for a cycloheximide-sensitive regulator of H-ferritin gene expression, since the presence of this protein synthesis inhibitor increased H-ferritin message levels, and in combination with TGF-beta1, cooperated in an additive manner to augment H-ferritin gene expression. These results show for the first time that TGF-beta1 can regulate ferritin gene expression in malignant H-ras transformed cells, and suggest a mechanism for growth factor stimulation of malignant cells, in which early alterations in the control of H-ferritin gene expression are important.

Quinolones as gonadotropin releasing hormone (GnRH) antagonists: simultaneous optimization of the C(3)-aryl and C(6)-substituents

A series of 3-arylquinolones was prepared and evaluated for their ability to act as gonadotropin releasing hormone (GnRH) antagonists. A variety of substitution patterns of the 3-aryl substituent are described. The 3,4,5-trimethylphenyl substituent (23h) was found to be optimal.

Aggressive thoracic actinomycosis complicated by vertebral osteomyelitis and epidural abscess leading to spinal cord compression

STUDY DESIGN

Report of a successfully diagnosed and treated case of spinal cord compression due to epidural actinomycosis.

OBJECTIVE

To illustrate that proper use of imaging strategy can greatly facilitate diagnosis and management of this rare condition.

SUMMARY OF BACKGROUND DATA

Spinal actinomycosis causing epidural abscess and significant spinal cord compression is an uncommon condition. Although diagnosis is difficult, favorable results are widely reported when specific therapy is instituted.

METHODS

A 32-year-old Chinese man had extensive dorsal thoracic soft tissue swelling and lower limb weakness. Collapse of the T5 vertebral body was found on plain radiographs with mediastinal infiltrates on chest radiograph. It took magnetic resonance imaging (MRI) to fully delineate the epidural abscess and dorsal muscular abscesses, which were not depicted by computed tomographic (CT) scan. Diagnosis was made by examination of CT-guided aspirate and tissue recovered during surgery by a microbiologist. The patient received high-dose intravenous penicillin and prompt spinal decompression once diagnosis of actinomycosis was confirmed.

RESULTS

The dorsal muscular abscesses and upper thoracic epidural abscess resolved rapidly after intravenous antibiotics and surgical drainage. This was well documented by follow-up MRI and the full recovery of motor power and lower limb sensation in the patient.

CONCLUSIONS

High clinical suspicion and proper use of imaging data led to timely diagnosis of this rare case of mediastinal, epidural, and intramuscular thoracic actinomycosis. Specific antibiotic therapy and timely, well-targeted surgical intervention greatly improve the outcome of this condition.

Altered states: involvement of phosphorylated CagA in the induction of host cellular growth changes by Helicobacter pylori

Helicobacter pylori, present in half of the world's population, is a very successful pathogen. It can survive for decades in the human stomach with few obvious consequences to the host. However, it is also the cause of gastric diseases ranging from gastritis to ulcers to gastric cancer and has been classified a type 1 carcinogen by the World Health Organization. We have previously shown that phosphorylation of a 145-kDa protein and activation of signal transduction pathways are associated with the attachment of H. pylori to gastric cells. Here we identify the 145-kDa protein as the H. pylori CagA protein. We also show that CagA is necessary to induce a growth-factor-like phenotype (hummingbird) in host gastric cells similar to that induced by hepatocyte growth factor (HGF). Additionally, we identify a second cellular phenotype induced after attachment by H. pylori, which we call SFA (stress fiber associated). SFA is CagA independent and is produced by type I and type II H. pylori.

Loss of Cul1 results in early embryonic lethality and dysregulation of cyclin E

The sequential timing of cell-cycle transitions is primarily governed by the availability and activity of key cell-cycle proteins. Recent studies in yeast have identified a class of ubiquitin ligases (E3 enzymes) called SCF complexes, which regulate the abundance of proteins that promote and inhibit cell-cycle progression at the G1-S phase transition. SCF complexes consist of three invariable components, Skp1, Cul-1 (Cdc53 in yeast) and Rbx1, and a variable F-box protein that recruits a specific cellular protein to the ubquitin pathway for degradation. To study the role of Cul-1 in mammalian development and cell-cycle regulation, we generated mice deficient for Cul1 and analysed null embryos and heterozygous cell lines. We show that Cul1 is required for early mouse development and that Cul1 mutants fail to regulate the abundance of the G1 cyclin, cyclin E (encoded by Ccne), during embryogenesis.