Relationship between plasma and bone concentrations of cefuroxime and flucloxacillin three different parenteral administrations compared in 30 arthroplasties

• (i) The objective was to determine the range of bone levels of cefuroxime and flucloxacillin achieved after one intravenous (IV) administration of different dosages of cefuroxime and flucloxacillin.
• (ii) Six groups of five patients participated in the study. The first three groups (A–C) received respectively 1500 mg, 1000 mg, and 500 mg cefuroxime intravenously and the second three groups (D–F) received 2000 mg, 1500 mg, and 1000 mg flucloxacillin intravenously.
• (iii) Parenteral administration of cefuroxime and flucloxacillin resulted in measurable bone concentrations in all patients.
• (iv) Large inter-individual variation in bone concentration was observed.
• (v) The bone concentrations of IV cefuroxime were higher (1500 mg, p = 0.0057; 1000 mg, p = 0.0260) than those of flucloxacillin. The bone concentrations of cefuroxime and flucloxacillin were dose dependent.

     

Fibrodysplasia ossificans progressiva: Still turning into wood after 300 years?

Fibrodysplasia ossificans progressiva (FOP), a rare autosomal dominant disorder, is characterized by symmetrical congenital skeletal abnormalities and progressive heterotopic ossification of the connective tissues. At present, more than 300 years after the first report by Patin in 1648 in which he described the woman who turned to wood, its pathogenesis remains largely unknown and its therapy is limited to symptom-modifying trials. However, significant progress has been recently made and new data on the molecular organization and regulation of normal and disordered bone induction are likely to lead to a more specific therapy. FOP is believed to be a genetic disorder characterized by a disturbed expression of the endochondral osteogenesis programme, and the remarkable clues from the fly reported by Kaplan et al. [8] in 1990 suggest a gain-of-function mutation in the genetic regulation of bone morphogenetic proteins.     

Cationic-amphiphilic arpromidine-derived guanidines and a histamine trifluoromethyl-toluidide derivative may activate pertussis toxin-sensitive G-proteins by a receptor-independent mechanism

Formyl peptides activate superoxide anion (O₂ ^–) formation in human neutrophils and in HL-60 cells via pertussis toxin (PTX)-sensitive guanine nucleotide-binding proteins (G-proteins), and histamine (HA) mediates inhibition of O₂ ^– formation via H₂-receptors. We have studied the effects of lipophilic arpromidine-derived guanidines, which are potent, full H₂-receptor agonists in the guinea pig atrium, on O₂ ^– formation and on activation of G-proteins in HL-60 membranes and on purified G-proteins. We have also studied the effects of a HA trifluoromethyl-toluidide derivative (HTMT), a cationic-amphiphilic HA derivative which activates O₂ ^– formation in HL-60 cells through a mechanism which is independent of known HA receptor subtypes, on G-protein activation. Guanidines, at concentrations, up to 30 mol/l inhibited and, at concentrations above 30 mol/l, enhanced formyl peptide-induce O₂ ^– formation in neutrophils. In HL-60 cells, guanidines per se activated O₂ ^– formation. The stimulatory effects of guanidines on O₂ ^– formation were not inhibited by H₁- or H₂-receptor antagonists. In HL-60 membranes, guanidines and HTMT, activated high-affinity GTPase in a PTX-sensitive manner. These substances also increased GTP hydrolysis effected by transducin and G_i/G_o-proteins. Our data suggest that lipophilic guanidines and HTMT may act as receptor-independent activators of PTX-sensitive G-proteins, resulting in stimulation of O ₂ ^– formation.     

Hard tissue laser ablation mechanisms

The aim of this work is the experimental and theoretical investigation of the influence of variable laser parameters (wavelength, fluence, pulse repetition rate) and of the optical and thermophysical properties of bone tissue (absorption coefficient, tissue inhomogeneity) as well as of the sample thickness on ablation thresholds and ablation rate. Ablation and perforation experiments were conducted using a semiconductively pre-ionized transverse excitation atmospheric pressure (TEA) carbon dioxide (CO₂) laser (10.6m and a sliding discharge TEA [hydrogen fluoride (HF)] laser (2.9m). The experimental data are discussed with respect to the following ablation mechanisms: thermal melting and vaporization process, pressure oscillation of gases released by the thermal decomposition of collagen and/or apatite, stresses due to the expansion of superheated water.     

Impact of different doses of ethinyl oestradiol on reduction of final height in constitutionally tall girls

Fifty-two tall girls were treated for constitutionally tall stature with different ethinyl oestradiol (EE) dosages. They were divided into three different treatment groups: group B (100 g EE/day;n=11); group C (300 g;n=25) and group D (500 g;n=16) and compared with an untreated group A (n=21) matched for age, height, bone age (BA) and height prediction. Using the height prediction method TW II, EE treatment reduced final height compared with the untreated girls in a weak dose-dependent manner, 2.3 cm (100 g/day), 3.0 cm (300 g/day), and 3.8 cm (500 g/day). Such a dose dependency was not found on applying the Bayley-Pineau height prediction method (100 g/day: 4.1 cm; 300 g/day: 4.2 cm; 500 g/day: 4.5 cm). However, there was a striking inverse correlation of the BA at the onset of treatment with the height reduction achieved using the TW II method (r: –0.43;P<0.001). Importantly, girls with a BA below 12 years at the onset of treatment experienced a height reduction of more than 6 cm.The EE dose used in the range of 100–500 g/day is not crucial for the amount of height reduction in tall girls. In general high dose EE treatment should be given restrictively, and especially so in girls with a BA (TW2 RUS-ZH) above 12.0 years.     

Five- to six-year results of a prospective clinical trial using the ENDOPORE dental implant and a mandibular overdenture

This report is an update on a group of 46 clinical trial patients who each received 3 free‐standing Endopore® dental implants placed using a 2‐stage surgical approach in the anterior mandible. After an initial healing interval of 10 weeks, the implants were used in each case to retain an overdenture, and at the time of the report. all patients had passed 5 years of continuous function. The 5‐year cumulative "survival" rate based on a life table analysis was 93.4% and this remained unchanged after 6 years. The 5‐year "success rate" was 83.3% when assessed qualitatively with the published criteria of others using a four‐field table analysis categorizing every implant in the study as one of "Grade 1 Success", "survival", "unaccounted for" or "failure". Modified periodontal parameters verified continued peri‐implant soft tissue health. No implant still in function had more than 1.8 mm cumulative bone loss during the first 5 years of function. These results provide clear evidence that Endopore® implants despite their short lengths function at least as well as other dental implant 1 designs used in much longer lengths.     

Precision and intersite correlation of bone densitometry at the radius, tibia and femur with peripheral quantitative CT

Objective. To compare the in situ precision of peripheral quantitative CT (pQCT) at the radius, tibia and femur, and to analyze the intersite correlation, in order to determine whether measurements at the lower extremity reproduce results at the radius or are of additional informative value. Design and material. pQCT measurements were performed in 86 elderly cadavers (mean age 80.5 years) at trabecular and cortical locations in the radius, tibia and femur, determining densitometric (bone mineral content and density) as well as geometric parameters (cross-sectional area, cortical thickness, polar moment of inertia and others). In 14 cadavers, repeated measurements were obtained at all sites on four different days. Results and conclusions. At cortical sites, the precision for the densitometric and geometric variables ranged from 0.4% to 4.3%, and was similar for the radius, tibia and femur. At trabecular locations, the reproducibility of the density measurements ranged from 1.8% to 2.5% at the radius, and from 3.2% to 5.9% at the femur and tibia. The intersite correlation of the total bone mineral content ranged from 0.87 and 0.97 at cortical sites, and from 0.63 to 0.85 at trabecular locations. The trabecular density showed a higher similarity between the tibia and femur (r=0.68–0.78) than between the radius and the lower extremity (r=0.41–0.45). The results demonstrate a substantial heterogeneity of trabecular bone in elderly individuals and advocate measurements directly at the site of clinical or scientific interest. Received: 5 July 1999 Revision requested: 12 August 1999 Revision received: 31 August 1999 Accepted: 13 September 1999     

Osteochondroma and secondary synovial osteochondromatosis

Secondary synovial osteochondromatosis (SOC) is a rare disorder caused by a variety of joint disorders. Two unusual cases of secondary SOC are presented. The first patient is a 43-year-old man with extensive SOC developing within a bursa surrounding an osteochondroma of the pubic bone. The second patient is a 23-year-old man who developed florid and progressive SOC of his hip joint following excision of a femoral neck osteochondroma. SOC recurred despite three excisions over a 15-month period. Imaging was useful in pre-operative diagnosis of bursal SOC in the first patient and in detecting multiple recurrences in the second patient. Both cases illustrate prominent SOC developing secondary to osteochondroma. The different hypotheses regarding bursal and secondary SOC are reviewed. Received: 8 October 1998 Revision requested: 28 October 1998 Revision received: 13 November 1998 Accepted: 16 November 1998     

Multiple single units and population responses during inhibitory gating of hippocampal auditory response in freely-moving rats

Paired clicks were presented to awake, freely-moving rats to examine neuronal activity associated with inhibitory gating of responses to repeated auditory stimuli. The rats had bundles of eight microwires implanted into each of four different brain areas: CA3 region of the hippocampus, medial septal nucleus, brainstem reticular nucleus, and the auditory cortex. Single-unit recordings from each wire were made while the local auditory-evoked potential was also recorded. The response to a conditioning stimulus was compared to the response to a test stimulus delivered 500 ms later: the ratio of the test response to the conditioning response provided a measure of inhibitory gating. Auditory-evoked potentials were recorded at all sites. Overall, brainstem reticular nucleus neurons showed the greatest gating of local auditory-evoked potentials, while the auditory cortex showed the least. However, except for the auditory cortex, both gating and non-gating of the evoked response were recorded at various times in all brain regions. Gating of the hippocampal response was significantly correlated with gating in the medial septal nucleus and brainstem reticular nucleus, but not the auditory cortex. Single-unit neuron firing in response to the clicks was most pronounced in the brainstem reticular nucleus and the medial septal nucleus, while relatively few neurons responded in the CA3 region of the hippocampus and the auditory cortex. Taken together, these data support the hypothesis that inhibitory gating of the auditory-evoked response originates in the non-lemniscal pathway and not in cortical areas of the rat brain.