Pathogenesis of osteoarthritis-like changes in the joints of mice deficient in type IX collagen

OBJECTIVE

To examine the pathogenetic mechanisms of osteoarthritis (OA)-like changes in Col9a1-/- mice, which are deficient in type IX collagen.

METHODS

Knee joints and temporomandibular joints (TMJs) from Col9a1-/- mice and their wild-type (Col9a1+/+) littermates were examined by light microscopy. Immunohistochemical staining was performed to examine the expression of matrix metalloproteinase 3 (MMP-3) and MMP-13, degraded type II collagen, and the discoidin domain receptor 2 (DDR-2) in knee joints. Cartilage mechanics were also evaluated for compressive properties by microindentation testing of the tibial plateau and for tensile properties by osmotic loading of the femoral condyle.

RESULTS

Histologic analysis showed age-dependent OA-like changes in the knee and TMJs of Col9a1-/- mice starting at the age of 3 months. At the age of 6 months, enhanced proteoglycan degradation was observed in the articular cartilage of the knee and TMJs of the mutant mice. The expression of MMP-13 and DDR-2 protein and the amount of degraded type II collagen were higher in the knee joints of Col9a1-/- mice than in their wild-type littermates at the age of 6 months. Changes in cartilage mechanics were observed in the femoral and tibial plateaus of Col9a1-/- mice at 6 months, including a decrease in the compressive modulus and uniaxial modulus. At 3 and 6 months of age, tibial cartilage in Col9a1-/- mice was found to be more permeable to fluid flow, with an associated compromise in the fluid pressurization mechanism of load support. All of these changes occurred only at medial sites.

CONCLUSION

Lack of type IX collagen in Col9a1-/- mice results in age-dependent OA-like changes in the knee joints and TMJs.

The management of life-threatening haemorrhage following blunt facial trauma

Life-threatening bleeding is uncommon following blunt facial trauma. There have been few reports in the literature describing its optimal management and a clear approach to treatment is yet to be defined. Reported strategies for control of facial haemorrhage include oro-nasal packing, external carotid artery ligation, transantral ligation of the internal maxillary artery, maxillary reduction and angiographic embolisation. Advances in angiography and selective vessel embolisation have made this the treatment of choice in cases of bleeding following penetrating facial injury. Its use in the management of bleeding following blunt facial trauma is unclear. The combined experience of the facial trauma teams at Harborview Hospital, Seattle, USA and Liverpool Hospital, Sydney, Australia yielded four cases of severe life-threatening haemorrhage following blunt trauma that underwent angiography. The roles of various management strategies were evaluated to generate a preferred management pathway in treating severe bleeding following blunt facial trauma.

Innovative technique for correction of the congenital lop ear

Congenital lop ear is a deformity affecting the upper third of the ear. It is characterised by varying degrees of lidding of the helix, reduction in the fossa triangularis, scapha compression, reduction or absence of the superior crus of the antihelix and an associated reduction in vertical height of the external ear. Reported strategies for the surgical correction of this deformity include simple excision of the excess overhanging cartilage, radial cartilage incisions of the helix to reverse its memory, various cartilage grafts from the surrounding ear or rib to strut or fill the defect, and mastoid hitching stitches to reinforce the repair. We present a novel technique using a reversed conchal cartilage graft to strut the deformed antihelix. The memory of the reversed conchal cartilage is used to correct lidding of the superior helix and obviates the need for intrinsic cartilage modification or excision. We have found a good aesthetic and structural result in a patient with bilateral congenital lop ear with 12 months follow up.

Consensus statement: medical management of acromegaly

In November 2003, the Pituitary Society and the European Neuroendocrine Association sponsored a consensus workshop in Seville to address challenging issues in the medical management of acromegaly. Participants comprised 70 endocrinologists and neurosurgeons with international expertise in managing patients with acromegaly. All participants participated in the workshop proceedings, and the final document written by the scientific committee reflects the consensus opinion of the interactive deliberations. The meeting was supported by an unrestricted educational grant from Ipsen. No pharmaceutical representatives participated in the program planning or in the scientific deliberations.

The effect of severe acute respiratory syndrome on emergency airway management

Study objectives: From early March 2003 to late May 2003, severe acute respiratory syndrome (SARS) was detected in Singapore. Two hundred thirty-eight patients were infected; 33 died. Forty-two percent were health care workers. The whole medical system in the country was put under stress. One major public hospital became the designated SARS hospital. Emergency cases were diverted to the remaining public hospitals, of which Singapore General Hospital was the main recipient. The increase in workload, new infection control procedures including mandatory wearing of the positive airway pressure respirator and personal protective equipment (PPE), and limiting the number of person-contacts with each patient were thought to affect resuscitation and airway management. Our aim is to study the effects of wearing of PPE and the restriction in number of resuscitation personnel on airway management during the SARS crisis.

Methods: The emergency department has an ongoing airway registry that prospectively captures patient demographics, diagnosis, indications for intubation, persons and discipline of intubating physician, number of attempts, method of intubation, success rates, and complications. The data were divided into 3 periods: (1) before PPE was instituted from November 1, 2002, to March 31, 2003; (2) during SARS (when PPE use was mandatory) from April 1 to July 31, 2003; and (3) after SARs (when PPE use was nonmandatory but encouraged) from August 1 to December 31, 2003.

Results: There was no change in patient demographics during the 3 periods, but there was a change in the patient diagnoses in period 2, with decreases in the proportion of respiratory and cardiac cases and increases in neurology and trauma cases. These changes reverted to the previous distribution in period 3. The alarming discovery was that whereas in period 1 (pre-SARS), resident medical officers attempted intubations 45% of the time, this figure went down to 35% in period 2 (SARS) and 23% in period 3 (post-SARS). Anesthetists performed 1.2%, 8%, and 0% of emergency intubations in periods 1, 2, and 3, respectively. Attending emergency physicians performed 54%, 56%, and 77% of intubations in periods 1, 2, and 3, respectively. The complication/peri-intubation event rates were 10.5%, 9.9%, and 9.4% in periods 1, 2, and 3, respectively. The success rate for residents was 80.8%, 89%, and 86.2% in periods 1, 2, and 3, respectively.

Conclusion: The wearing of PPE and positive airway pressure respirator is thought to make intubation more difficult, as seen by the increase in proportion of intubations performed by anesthetists in period 2 and by attending emergency physicians in periods 2 and 3. The infection control policy that restricts the number of health care staff attending to each patient may have influenced the department's decision to allow only the most confident or experienced personnel to manage the airway. The exposure of junior residents in emergency airway management during SARS and the immediate post-SARS period was decreased. This trend should be further monitored, and intervention may be necessary should it continue to decline.

Pharmacological characterization of glutamatergic agonists and antagonists at recombinant human homomeric and heteromeric kainate receptors in vitro

An increasing body of evidence suggests that native kainate receptors form ion channels from homomeric and heteromeric combinations of five receptor subunits: GluR5, GluR6, GluR7, KA1 and KA2. We have examined the activity of agonists and antagonists at recombinant human kainate receptors expressed in HEK293 cells, using both whole-cell electrophysiological recording and 96-well plate fluo-3 based calcium microfluorimetry (FLIPR). Both homomeric (GluR5 and GluR6) and heteromeric (GluR5/6, GluR5/KA2 and GluR6/KA2) receptors were examined. Heteromeric receptor assemblies showed electrophysiological and pharmacological profiles which were distinct from homomeric channels. Several agonists, including AMPA, ATPA and (S)-5-iodowillardiine, and antagonists, including gamma-D-glutamylaminomethylsulphonic acid (GAMS) and the decahydroisoquinoline compounds LY293558, LY377770 and LY382884, were found to act at GluR5-containing channels while having no effect at GluR6 homomers. AMPA, ATPA and (S)-5-iodowillardiine did activate GluR6/KA2 heteromers, but only as partial agonists. Additionally, ATPA was shown to act as an antagonist at homomeric GluR6 receptors at high concentrations (IC50 approximately 2 mM). Kynurenic acid was also found to differentiate between GluR6 and GluR6/KA2 receptors, antagonizing glutamate at GluR6 (IC50 = 0.4 mM), while having no effect at GluR6/KA2 channels. The results of the current study provide a broad pharmacological characterization of both homomeric and heteromeric recombinant human kainate receptors, and identify which compounds are likely to be useful tools for studying these various receptor subtypes.

Intravenous administration of an AAV-2 vector for the expression of factor IX in mice and a dog model of hemophilia B

Previous experiments have demonstrated the stable expression of factor IX (FIX) protein in mice and canine models of hemophilia B following portal vein gene transfer with a recombinant adeno-associated virus (rAAV) vector encoding FIX. Here, we present the results of studies that further optimized the rAAV vector transgene cassette used to express FIX and explored the use of the less-invasive intravenous (i.v.) route of vector administration for the treatment of hemophilia B. First, a liver-specific promoter was evaluated in conjunction with cis-acting regulatory elements in mice. Constructs that included both the beta-globin intron and the woodchuck hepatitis virus post-transcriptional regulatory element resulted in the highest level of FIX expression in vivo. Using this optimized vector, we demonstrate that i.v. injection was feasible for hepatic gene transfer in mice, achieving 70-80% of portal vein expression levels of FIX. In further studies using the Chapel Hill strain of hemophilia B dogs, we demonstrate for the first time FIX expression and partial correction of the bleeding disorder following i.v. administration of an AAV vector.

Diagnosis and treatment of acromegaly complications

The Pituitary Society in conjunction with the European Neuroendocrine Association held a consensus workshop to develop guidelines for diagnosis and treatment of the co-morbid complications of acromegaly. Fifty nine pituitary specialists (endocrinologists, neurosurgeons and cardiologists) assessed the current published literature on acromegaly complications in light of recent advances in maintaining tight therapeutic control of GH hypersecretion. The impact of elevated GH levels on cardiovascular disease, hypertension, diabetes, sleep apnea, colon polyps, bone disease, reproductive disorders, and neuropsychologic complications were considered. Guidelines are proposed for effective management of these complications in the context of overall acromegaly control. When appropriate, requirements for prospective evidence-based studies and surveillance database development are enunciated. Effective management of co-morbid acromegaly complications will lead to improved morbidity and mortality in acromegaly.

Vitamin D receptor start codon polymorphism (Fok I) and bone mineral density in Chinese men and women

The relationship between Fok I polymorphism of the vitamin D receptor start codon, bone mineral density (BMD) and vertebral fractures was studied in 684 Chinese men and women. A significant trend was observed only in Chinese women aged 70-79 years. The mean BMD at the total body was 0.85 +/- 0.01 g/cm2, 0.82 +/- 0.01 g/cm2 and 0.84 +/- 0.01 g/cm2 for elderly women of the FF, Ff and ff genotypes respectively (p = 0.06 by ANOVA). Similar but statistically non-significant trends were observed at the hip and spine. However, no association between BMD and the Fok I genotype was observed in younger women (aged 50-59 years) and elderly men (aged 70-79 years). In all study groups, there was no effect of an interaction between Fok I polymorphism and calcium intake on BMD (p > 0.05 for the interaction effects by two-way ANOVA). No significant association was observed between Fok I polymorphism and vertebral fracture in elderly men or women (p > 0.05 by the chi-square test). We conclude that the Fok I polymorphism may have a weak effect on the BMD of elderly Chinese women.

A microsatellite sequence from the rice blast fungus (Magnaporthe grisea) distinguishes between the centromeres of Hordeum vulgare and H. bulbosum in hybrid plants

A TC/AG-repeat microsatellite sequence derived from the rice blast fungus (Magnaporthe grisea) hybridized to all of the centromeres of Hordeum vulgare chromosomes, but hybridized faintly or not at all to the chromosomes of Hordeum bulbosum. Using this H. vulgare centromere-specific probe, the chromosomes of four F1 hybrids between H. vulgare and H. bulbosum were analyzed. The chromosome constitution in the root tips of the hybrids was mosaic, i.e., 7 (7v, H. vulgare) and 14 (7v + 7b H. bulbosum), or 14 (7v + 7b) and 27 (14v + 13b), or 7 (7v), 14 (7v + 7b), and 27 (14v + 13b). The 27-chromosome tetraploid hybrid cells were revealed to have the NOR (nucleolus organizer region) bearing chromosome of H. bulbosum in a hemizygous state, which might indicate some role for this chromosome in the chromosome instability of the hybrid condition. The chromosomal distribution showed that the chromosomes of H. vulgare were concentric and chromosomes of H. bulbosum were peripheral in the mitotic squash. This non-random chromosome distribution and the centromere-specific repeated DNA differences in the two species were discussed in relation to H. bulbosum chromosome elimination. Meiotic chromosome analyses revealed a high frequency of homoeologous chromosome pairing in early prophase. However, this chromosome pairing did not persist until later meiotic stages and many univalents and chromosome fragments resulted. These were revealed to be H. bulbosum by fluorescence in situ hybridization (FISH) analysis with the H. vulgare centromere-specific probe. Because the chromosome segregation of H. vulgare and H. bulbosum chromosomes at anaphase I of meiosis was random, the possibility for obtaining chromosome substitution lines in diploid barley from the diploid hybrid was discussed.

Lower hypertension prevalence in first-generation African immigrants compared to US-born African Americans

Both genetic and environmental factors have been hypothesized to explain the higher prevalence of hypertension in US African Americans compared to populations still residing in western Africa. Studies of first-generation immigrants can help to identify risk factors for increased chronic disease expression in the developed world. Since we could identify no prior studies of hypertension in African immigrants to the United States, we conducted a cross-sectional survey of African-born and US-born African-American health professionals to compare the two groups for the prevalence of hypertension (blood pressure > or = 140/90 mm Hg or use of antihypertensive medication) and risk factors for hypertension (body mass index, lifestyle factors, and psychosocial variables hypothesized to relate to hypertension). Subjects were registered pharmacists and nurses recruited by mail. For the 182 individuals who completed study measurements (95 US-born and 87 African-born), the unadjusted odds ratio for hypertension associated with birthplace was 2.16 (95% CI = 1.12, 3.98). After adjustment for body mass index and age, the OR for birthplace was 1.92 (95% CI = 0.92, 4.00). No lifestyle or psychosocial variables were associated with hypertension prevalence. We conclude that there is a lower prevalence of hypertension in first-generation African immigrants that cannot be readily explained by the environmental effects measured in this study. Larger scale studies with African immigrants could advance understanding of the causes of the increased hypertension prevalence in US-born African Americans.

Effect of low molecular weight heparin on bone metabolism and hyperlipidemia in patients on maintenance hemodialysis

The effect of low molecular weight heparin (LMWH) on serum lipid profile in hemodialysis remains controversial and its effect on bone metabolism has not been studied. A crossover study was conducted in 40 patients on stable hemodialysis using unfractionated heparin (UFH) for more than 24 months. These patients were then treated with a LMWH (nadroparin-Ca) for 8 months during hemodialysis and subsequently switched back to UFH for 12 months. Serum lipid profile, biochemical markers for bone metabolism, and bone densitometry (BMD) were monitored at four-month intervals while all medications remained unchanged. Cholesterol (TC), triglyceride (TG), low-density lipoprotein-cholesterol (LDL-C), lipoprotein(a) (Lp(a)), apolipoprotein B (Apo B) were raised in 35%, 29%, 12%, 24% and 24% of patients respectively. High-density lipoprotein-cholesterol (HDL-C) and apolipoprotein A1 (Apo A-1) were reduced in 47% and 9% of patients. Bone-specific alkaline phosphatase (BALP) and intact osteocalcin (OSC), both reflecting osteoblastic activity, were raised in 65% and 94% of patients. Tartrate-resistant acid phosphatase (TRACP) reflecting osteoclastic activity and parathyroid hormone (PTH) were elevated in 35% and 88% of patients. Following LMWH treatment, TC, Tg, Lp(a) and Apo B were reduced by 7%, 30%, 21% and 10% respectively (p<0.05 or <0.01) while Apo A-1 were raised by 7% (p<0.01). Simultaneously, TRACP was reduced by 13% (p<0.05). These biochemical changes were detected soon after 4 months of LMWH administration. Although BMD values in our patients were lower than those of age-matched normal subjects, significant changes were not observed with LMWH treatment. After switching back to UFH for hemodialysis, these biochemical indices reverted to previous values during UFH treatment with a significant higher level in TC and Apo B while serum Apo A-1 remained elevated. Our study suggests LMWH may partially alleviate hyperlipidemia and, perhaps, osteoporosis associated with UFH administration in patients on maintenance hemodialysis.

Pharmacological aids for smoking cessation

To smokers, nicotine addiction is a powerful vice that is difficult to overcome even with pharmaceutical aids. Relapse rates are high and maintaining a successful quitting strategy is difficult regardless of the method used. Therefore, clinicians should routinely provide positive feedback to help maintain their patients' cessation. Encouraging smoking cessation, selecting appropriate products, and monitoring and supporting patients through their withdrawal symptoms makes for a more complete therapeutic care plan for cessation of tobacco use. In the long term, helping patients to succeed in their cessation treatment has the potential to reduce healthcare costs, save clinicians time and money, and improve morbidity and mortality rates.

Novel AMPA receptor potentiators LY392098 and LY404187: effects on recombinant human AMPA receptors in vitro

The present study describes the activity of two novel potent and selective AMPA receptor potentiator molecules LY392098 and LY404187. LY392098 and LY404187 enhance glutamate (100 microM) stimulated ion influx through recombinant homomeric human AMPA receptor ion channels, GluR1-4, with estimated EC(50) values of 1.77 microM (GluR1(i)), 0.22 microM (GluR2(i)), 0.56 microM (GluR2(o)), 1.89 microM (GluR3(i)) and 0.20 microM (GluR4(i)) for LY392098 and EC(50) values of 5.65 microM (GluR1(i)), 0.15 microM (GluR2(i)), 1.44 microM (GluR2(o)), 1.66 microM (GluR3(i)) and 0.21 microM (GluR4(i)) for LY404187. Neither compound affected ion influx in untransfected HEK293 cells or GluR transfected cells in the absence of glutamate. Both compounds were selective for activity at AMPA receptors, with no activity at human recombinant kainate receptors. Electrophysiological recordings demonstrated that glutamate (1 mM)-evoked inward currents in human GluR4 transfected HEK293 cells were potentiated by LY392098 and LY404187 at low concentrations (3-10 nM). In addition, both compounds removed glutamate-dependent desensitization of recombinant GluR4 AMPA receptors. These studies demonstrate that LY392098 and LY404187 allosterically potentiate responses mediated by human AMPA receptor ion channels expressed in HEK 293 cells in vitro.