Not All Binding Sites Are Equal: Site Determination and Folding State Analysis of Gas-Phase Protein-Metallodrug Adducts

Modern approaches in metallodrug research focus on compounds that bind protein targets rather than DNA. However, the identification of protein targets and binding sites is challenging. Using intact mass spectrometry and proteomics, we investigated the binding of the antimetastatic agent RAPTA-C to the model proteins ubiquitin, cytochrome c, lysozyme, and myoglobin. Binding to cytochrome c and lysozyme was negligible. However, ubiquitin bound up to three Ru moieties, two of which were localized at Met1 and His68 as [Ru(cym)], and [Ru(cym)] or [Ru(cym)(PTA)] adducts, respectively. Myoglobin bound up to four [Ru(cym)(PTA)] moieties and five sites were identified at His24, His36, His64, His81/82 and His113. Collision-induced unfolding (CIU) studies via ion-mobility mass spectrometry allowed measuring protein folding as a function of collisional activation. CIU of protein-RAPTA-C adducts showed binding of [Ru(cym)] to Met1 caused a significant compaction of ubiquitin, likely from N-terminal S-Ru-N chelation, while binding of [Ru(cym)(PTA)] to His residues of ubiquitin or myoglobin induced a smaller effect. Interestingly, the folded state of ubiquitin formed by His functionalization was more stable than Met1 metalation. The data suggests that selective metalation of amino acids at different positions on the protein impacts the conformation and potentially the biological activity of anticancer compounds.

AdductHunter: identifying protein-metal complex adducts in mass spectra

Mass spectrometry (MS) is an analytical technique for molecule identification that can be used for investigating protein-metal complex interactions. Once the MS data is collected, the mass spectra are usually interpreted manually to identify the adducts formed as a result of the interactions between proteins and metal-based species. However, with increasing resolution, dataset size, and species complexity, the time required to identify adducts and the error-prone nature of manual assignment have become limiting factors in MS analysis. AdductHunter is a open-source web-based analysis tool that  automates the peak identification process using constraint integer optimization to find feasible combinations of protein and fragments, and dynamic time warping to calculate the dissimilarity between the theoretical isotope pattern of a species and its experimental isotope peak distribution. Empirical evaluation on a collection of 22 unique MS datasetsshows fast and accurate identification of protein-metal complex adducts in deconvoluted mass spectra.

Radiographic considerations for pediatric supracondylar humerus fractures

Although supracondylar humerus fractures are common pediatric injuries, guidelines for postoperative imaging remain unclear. This study's purpose was to evaluate decision-making at various points in the postoperative period. The secondary objective was to compare the use of mini C arm fluoroscopy and flat plate X-rays at the first postoperative visit. A retrospective, cohort study was performed at one level I trauma center. Patients ages 1 to 14 with extension Gartland type II-IV supracondylar fractures sustained between January 2013 and May 2020 and treated with closed or open reduction and percutaneous fixation were included. Data collected included demographics, fracture characteristics, and imaging information. Of 553 patients who underwent surgery, 375 (67.8%) received intraoperative images after casting; none resulted in an intraoperative intervention. Of 463 patients with imaging at first follow-up, nine (1.9%) had a management modification, including seven for loss of reduction, all determined by the original operating surgeon. The method of imaging, did not differ significantly with respect to revision surgery. Twenty-six (4.0%) of 532 patients with imaging at pin removal received additional casting after pin removal, but no patients had their pins retained. This retrospective study examined the efficacy of imaging in pediatric supracondylar fractures. Intraoperative, postcasting images did not change management and should be discontinued. Imaging at first follow-up can be useful in identifying patients with loss of reduction and mini C arm serves as a viable alternative to standard X-rays. Finally, imaging at pin removal resulted in additional casting only in type III fractures. Level of evidence: Level III-retrospective, cohort study.

Platinum(terpyridine) complexes with N-heterocyclic carbene co-ligands: high antiproliferative activity and low toxicity in vivo

Pt(terpyridine) complexes are well-known DNA intercalators. The introduction of an NHC co-ligand rendered such a complex highly antiproliferative in cancer cells compared to its chlorido derivative. Despite the high potency, zebrafish embryos tolerated the compound well, especially compared to cisplatin. DNA interaction studies support a mode of action related to intercalation.

Perforation of the Knee Joint Following Antegrade Intramedullary Nailing of a Comminuted Femoral Diaphyseal Fracture: A Case Report

A 63-year-old man with a comminuted spiral femoral shaft fracture was treated with closed reduction and internal fixation with a cephalomedullary nail. Two weeks postoperatively, one of the two static distal interlocking bolts began backing out and was removed. The nail ultimately migrated distally and perforated the knee joint at four months postoperatively. The patient was successfully treated with an exchange nail and percutaneous bone graft to the fracture site.

A single static distal interlocking bolt may be inadequate to maintain length in a healing comminuted spiral femur shaft. Multiple distal interlocking bolts should be in place until the completion of fracture healing.

Anthracenyl Functionalization of Half-Sandwich Carbene Complexes: In Vitro Anticancer Activity and Reactions with Biomolecules

N-Heterocyclic carbene (NHC) ligands are widely investigated in medicinal inorganic chemistry. Here, we report the preparation and characterization of a series of half-sandwich [M(L)(NHC)Cl₂] (M = Ru, Os, Rh, Ir; L = cym/Cp*) complexes with a N-flanking anthracenyl moiety attached to imidazole- and benzimidazole-derived NHC ligands. The anticancer activity of the complexes was investigated in cell culture studies where, in comparison to a Rh derivative with an all-carbon-donor-atom-based ligand (5a), they were found to be cytotoxic with IC₅₀ values in the low micromolar range. The Ru derivative 1a was chosen as a representative for stability studies as well as for biomolecule interaction experiments. It underwent partial chlorido/aqua ligand exchange in DMSO-d₆/D₂O to rapidly form an equilibrium in aqueous media. The reactions of 1a with biomolecules proceeded quickly and resulted in the formation of adducts with amino acids, DNA, and protein. Hen egg white lysozyme crystals were soaked with 1a, and the crystallographic analysis revealed an interaction with an l-aspartic acid residue (Asp119), resulting in the cleavage of the p-cymene ligand but the retention of the NHC moiety. Cell morphology studies for the Rh analog 3a suggested that the cytotoxicity is exerted via mechanisms different from that of cisplatin.

Probing the Paradigm of Promiscuity for N-Heterocyclic Carbene Complexes and their Protein Adduct Formation

Metal complexes can be considered a "paradigm of promiscuity" when it comes to their interactions with proteins. They often form adducts with a variety of donor atoms in an unselective manner. We have characterized the adducts formed between a series of isostructural N-heterocyclic carbene (NHC) complexes with Ru, Os, Rh, and Ir centers and the model protein hen egg white lysozyme by X-ray crystallography and mass spectrometry. Distinctive behavior for the metal compounds was observed with the more labile Ru and Rh complexes targeting mainly a surface l-histidine moiety through cleavage of p-cymene or NHC co-ligands, respectively. In contrast, the more inert Os and Ir derivatives were detected abundantly in an electronegative binding pocket after undergoing ligand exchange of a chlorido ligand for an amino acid side chain. Computational studies supported the binding profiles and hinted at the role of the protein microenvironment for metal complexes eliciting selectivity for specific binding sites on the protein.

Triazolyl-Functionalized N-Heterocyclic Carbene Half-Sandwich Compounds: Coordination Mode, Reactivity and in vitro Anticancer Activity

We report investigations on the anticancer activity of organometallic [M^II/III (η⁶ -p-cymene/η⁵ -pentamethylcyclopentadienyl)] (M=Ru, Os, Rh, and Ir) complexes of N-heterocyclic carbenes (NHCs) substituted with a triazolyl moiety. Depending on the precursors, the NHC ligands displayed either mono- or bidentate coordination via the NHC carbon atom or as N,C-donors. The metal complexes were investigated for their stability in aqueous solution, with the interpretation supported by density functional theory calculations, and reactivity to biomolecules. In vitro cytotoxicity studies suggested that the nature of both the metal center and the lipophilicity of the ligand determine the biological properties of this class of compounds. The Ir^III complex 5 d bearing a benzimidazole-derived ligand was the most cytotoxic with an IC₅₀ value of 10 μM against NCI-H460 non-small cell lung carcinoma cells. Cell uptake and distribution studies using X-ray fluorescence microscopy revealed localization of 5 d in the cytoplasm of cancer cells.

Mustards-Derived Terpyridine-Platinum Complexes as Anticancer Agents: DNA Alkylation vs Coordination

The development of bifunctional platinum complexes with the ability to interact with DNA via different binding modes is of interest in anticancer metallodrug research. Therefore, we report platinum(II) terpyridine complexes to target DNA by coordination and/or through a tethered alkylating moiety. The platinum complexes were evaluated for their in vitro antiproliferative properties against the human cancer cell lines HCT116 (colorectal), SW480 (colon), NCI-H460 (non-small cell lung), and SiHa (cervix) and generally exhibited potent antiproliferative activity although lower than their respective terpyridine ligands. ¹H NMR spectroscopy and/or ESI-MS studies on the aqueous stability and reactivity with various small biomolecules, acting as protein and DNA model compounds, were used to establish potential modes of action for these complexes. These investigations indicated rapid binding of complex PtL3 to the biomolecules through coordination to the Pt center, while PtL4 in addition alkylated 9-ethylguanine. PtL3 was investigated for its reactivity to the model protein hen egg white lysozyme (HEWL) by protein crystallography which allowed identification of the N^δ1 atom of His15 as the binding site.

Three-dimensional Computed Tomography Posterior Iliac Oblique Images Enhance Preoperative Planning for Acetabular Fracture Surgery

The advent of computed tomography and development of three-dimensional (3-D) reconstructions has allowed for profound advances in the understanding of complex acetabular fractures. The authors sought to determine the impact of 3-D reconstructions on understanding of the morphology of these injuries. A survey of 20 fellowship-trained orthopaedic trauma surgeons was undertaken to assess the utility of these reconstructions on understanding three complex posterior acetabulum fractures. Respondents noted significantly better understanding of posterior wall and transverse-posterior wall fracture patterns compared to a posterior column-posterior wall pattern when utilizing two-dimensional imaging only. The respondent#x02019;s understanding of all three patterns was improved with the addition of 3-D reconstructions. With regards to individual images, posterior iliac oblique reconstructions obtained at 36-degree and 54-degree from posterior were reported to be most helpful in improving understanding of fracture morphology. Three-dimensional reconstructions of posterior acetabular fractures are effective in enhancing understanding of fracture morphology. (Journal of Surgical Orthopaedic Advances 30(1):050-054, 2021).

A Combined Spectroscopic and Protein Crystallography Study Reveals Protein Interactions of RhI(NHC) Complexes at the Molecular Level

While most Rh-N-heterocyclic carbene (NHC) complexes currently investigated in anticancer research contain a Rh(III) metal center, an increasing amount of research is focusing on the cytotoxic activity and mode of action of square-planar [RhCl(COD)(NHC)] (where COD = 1,5-cyclooctadiene) which contains a Rh(I) center. The enzyme thioredoxin reductase (TrxR) and the protein albumin have been proposed as potential targets, but the molecular processes taking place upon protein interaction remain elusive. Herein, we report the preparation of peptide-conjugated and its nonconjugated parent [RhCl(COD)(NHC)] complexes, an in-depth investigation of both their stability in solution, and a crystallographic study of protein interaction. The organorhodium compounds showed a rapid loss of the COD ligand and slow loss of the NHC ligand in aqueous solution. These ligand exchange reactions were reflected in studies on the interaction with hen egg white lysozyme (HEWL) as a model protein in single-crystal X-ray crystallographic investigations. Upon treatment of HEWL with an amino acid functionalized [RhCl(COD)(NHC)] complex, two distinct rhodium adducts were found initially after 7 d of incubation at His15 and after 4 weeks also at Lys33. In both cases, the COD and chlorido ligands had been substituted with aqua and/or hydroxido ligands. While the histidine (His) adduct also indicated a loss of the NHC ligand, the lysine (Lys) adduct retained the NHC core derived from the amino acid l-histidine. In either case, an octahedral coordination environment of the metal center indicates oxidation to Rh(III). This investigation gives the first insight on the interaction of Rh(I)(NHC) complexes and proteins at the molecular level.

Anatomic considerations for retrograde fibular medullary screw insertion: a cadaveric study

OBJECTIVES

A retrograde fibular medullary screw may be utilized in certain fractures about the ankle. The purpose of this study is to investigate the anatomic considerations of a retrograde medullary screw inserted from a lateral starting point to nearby anatomic structures about the distal fibula.

METHODS

Ten fresh-frozen cadaveric lower extremities were utilized. A 1.6-mm Kirschner wire was inserted into the distal fibula from a far-lateral starting point. A 3.2-mm cannulated drill bit was then inserted over the Kirschner wire. After placement of the drill bit, dissection of the lateral ankle was undertaken. The proximity of nearby anatomic structures to the drill bit was measured using calipers. A 4.5-mm cortical screw was then inserted using fluoroscopic guidance. Measurements were then taken again to assess the relationship of the screw head to adjacent structures.

RESULTS

Mean distance from drill bit to nearby structures is as follows: Peroneus longus tendon 4.56 mm, peroneus brevis tendon 6.62 mm, sural nerve 4.13 mm, superior peroneal retinaculum 7.52 mm, inferior peroneal retinaculum 6.61 mm, anterior talofibular ligament (ATFL) 6.1 mm, calcaneofibular ligament (CFL) 6.7 mm. Average distance from 4.5-mm screw head to nearby structures is as follows: peroneus longus tendon 6.79 mm, peroneus brevis tendon 6.73 mm, ATFL 4.16 mm, CFL 5.14 mm, lateral talar process 9.41 mm.

CONCLUSION

Retrograde medullary fibular screw fixation may be safely carried out through a lateral start point. Anatomic structures about the lateral ankle are nearby but not immediately adjacent to the drill bit.

A Comparison of Complications and Union Rates in Intramedullary Nailing of Femoral Shaft Fractures Treated With Open Versus Closed Reduction

Intramedullary rod fixation is a common technique for treatment of femoral shaft fractures, with both open and closed reduction techniques described. The purpose of this study was to assess union and complication rates among patients treated with open vs closed reduction and intramedullary nailing of closed femoral shaft fractures. A total of 107 patients undergoing intramedullary fixation of nonpathologic femoral shaft fractures (AO/OTA type 32) between January 2012 and June 2017 were retrospectively studied. Those undergoing open reduction prior to intramedullary nailing were compared with those undergoing closed reduction. The primary outcome analyzed was union rate. Secondary outcomes were time to union, complications necessitating return to the operating room, and operative times. Mean follow-up was 14 months in both groups (range, 6-48 months). Of the 107 patients, 34.6% (n=37) underwent open reduction and 65.4% (n=70) underwent closed reduction. Patients in the open reduction group had rates of union (89.1%, 33 of 37) similar to those of patients in the closed reduction group (92.9%, 65 of 70; P=.378). Patients in the open reduction group who had union did so in a mean of 6.2 months (range, 3-12 months) vs a mean of 5.4 months (range, 2-11 months) in the closed reduction group (P=.13). Six patients (16.2%) in the open reduction group and 6 patients (8.6%) in the closed reduction group had a postoperative complication requiring return to the operating room (P=.18). Open reduction and intramedullary nailing results in rates of union, time to union, and rates of significant complications similar to those of closed reduction and intramedullary nailing. [Orthopedics. 2020; 43(2): 103-107.].

Potent Inhibition of Thioredoxin Reductase by the Rh Derivatives of Anticancer M(arene/Cp*)(NHC)Cl2 Complexes

Metal complexes provide a versatile platform to develop novel anticancer pharmacophores, and they form stable compounds with N-heterocyclic carbene (NHC) ligands, some of which have been shown to inhibit the cancer-related selenoenzyme thioredoxin reductase (TrxR). To expand a library of isostructural NHC complexes, we report here the preparation of Rh^III- and Ir^III(Cp*)(NHC)Cl₂ (Cp* = η⁵-pentamethylcyclopentadienyl) compounds and comparison of their properties to the Ru^II- and Os^II(cym) analogues (cym = η⁶-p-cymene). Like the Ru^II- and Os^II(cym) complexes, the Rh^III- and Ir^III(Cp*) derivatives exhibit cytotoxic activity with half maximal inhibitory concentration (IC₅₀) values in the low micromolar range against a set of four human cancer cell lines. In studies on the uptake and localization of the compounds in cancer cells by X-ray fluorescence microscopy, the Ru and Os derivatives were shown to accumulate in the cytoplasmic region of treated cells. In an attempt to tie the localization of the compounds to the inhibition of the tentative target TrxR, it was surprisingly found that only the Rh complexes showed significant inhibitory activity at IC₅₀ values of ∼1 μM, independent of the substituents on the NHC ligand. This indicates that, although TrxR may be a potential target for anticancer metal complexes, it is unlikely the main target or the sole target for the Ru, Os, and Ir compounds described here, and other targets should be considered. In contrast, Rh(Cp*)(NHC)Cl₂ complexes may be a scaffold for the development of TrxR inhibitors.

Gel electrophoresis in combination with laser ablation-inductively coupled plasma mass spectrometry to quantify the interaction of cisplatin with human serum albumin

Cisplatin and its second and third generation analogues are widely used in the treatment of cancer. To study their reactions with proteins, we present a method based on SDS-PAGE separation and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) for platinum detection in the reaction between human serum albumin (HSA) and cisplatin. We developed matrix-matched standards of HSA/cisplatin mixtures and used them to quantify the amount of adducts formed at different HSA:cisplatin ratios. We noted that cisplatin incubation with HSA resulted in the formation of higher order HSA n-mers, depending on the amount of cisplatin added. This caused a depletion of the HSA dimer bands, while the majority of HSA was present as the monomer. Inducing the formation of such higher molecular weight species may have an impact on the mode of action of metallodrugs.

Correction: Unexpected arene ligand exchange results in the oxidation of an organoruthenium anticancer agent: the first X-ray structure of a protein–Ru(carbene) adduct

Correction for ‘Unexpected arene ligand exchange results in the oxidation of an organoruthenium anticancer agent: the first X-ray structure of a protein–Ru(carbene) adduct’ by Matthew P. Sullivan et al., Chem. Commun., 2018, 54, 6120–6123.

A method for analyzing the composition of viral nucleoprotein complexes, produced by heterologous expression in bacteria

Viral genomes are protected and organized by virally encoded packaging proteins. Heterologous production of these proteins often results in formation of particles resembling the authentic viral capsid or nucleocapsid, with cellular nucleic acids packaged in place of the viral genome. Quantifying the total protein and nucleic acid content of particle preparations is a recurrent biochemical problem. We describe a method for resolving this problem, developed when characterizing particles resembling the Menangle Virus nucleocapsid. The protein content was quantified using the biuret assay, which is largely independent of amino acid composition. Bound nucleic acids were quantified by determining the phosphorus content, using inductively coupled plasma mass spectrometry. Estimates for the amount of RNA packaged within the particles were consistent with the structurally-characterized packaging mechanism. For a bacterially-produced nucleoprotein complex, phosphorus usually provides a unique elemental marker of bound nucleic acids, hence this method of analysis should be routinely applicable.

Use of the physical environment to support everyday activities for people with dementia: A systematic review

Difficulty with everyday activities is a key symptom and defining feature of dementia, relating to subjective reports of well-being and overall quality of life. One way to support individuals in their daily activities is by modifying the physical environment to make it easier to interact with during activity performance. This systematic review explores the range of studies available using physical environmental strategies to support performance in everyday activities for people with dementia. Seventy-two relevant studies were identified by the search. Physical environmental strategies included changes to the global environment and to architectural features, use of moveable environmental aids and tailored individual approaches. Strategies supported general everyday activity functioning (N = 19), as well as specific activities, particularly mealtimes (N = 15) and orientation in space (N = 16); however, few studies were found that focused on aspects of personal care such as dressing (N = 1) and showering or the preferred hobbies of individuals (N = 0). Overall, there appeared to be a lack of research within private home environments, and of studies which specify the dementia syndrome or the whole neuropsychological profile of people with dementia. More work is needed to extend theoretical understandings of how people with dementia interact with their environments so that these spaces can be designed to further support activities of daily living performance. Future work in this field could also incorporate the perspectives and preferences of those living with dementia.

Antitumor Metallodrugs that Target Proteins

Anticancer platinum-based drugs are widely used in the treatment of a variety of tumorigenic diseases. They have been identified to target DNA and thereby induce apoptosis in cancer cells. Their reactivity to biomolecules other than DNA has often been associated with side effects that many cancer patients experience during chemotherapy. The development of metal compounds that target proteins rather than DNA has the potential to overcome or at least reduce the disadvantages of commonly used chemotherapeutics. Many exciting new metal complexes with novel modes of action have been reported and their anticancer activity was linked to selective protein interaction that may lead to improved accumulation in the tumor, higher selectivity and/or enhanced antiproliferative efficacy. The development of new lead structures requires bioanalytical methods to confirm the hypothesized modes of action or identify new, previously unexplored biological targets and pathways. We have selected original developments for review in this chapter and highlighted compounds on track toward clinical application.

Antitumor Metallodrugs that Target Proteins

Anticancer platinum-based drugs are widely used in the treatment of a variety of tumorigenic diseases. They have been identified to target DNA and thereby induce apoptosis in cancer cells. Their reactivity to biomolecules other than DNA has often been associated with side effects that many cancer patients experience during chemotherapy. The development of metal compounds that target proteins rather than DNA has the potential to overcome or at least reduce the disadvantages of commonly used chemotherapeutics. Many exciting new metal complexes with novel modes of action have been reported and their anticancer activity was linked to selective protein interaction that may lead to improved accumulation in the tumor, higher selectivity and/or enhanced antiproliferative efficacy. The development of new lead structures requires bioanalytical methods to confirm the hypothesized modes of action or identify new, previously unexplored biological targets and pathways. We have selected original developments for review in this chapter and highlighted compounds on track toward clinical application.

Unexpected arene ligand exchange results in the oxidation of an organoruthenium anticancer agent: the first X-ray structure of a protein–Ru(carbene) adduct

The first crystallographic study of a Ru(carbene)–protein adduct is complemented by EPR spectroscopy showing Ru oxidation upon binding.

Current Management of Talar Fractures

Talar fractures are some of the most challenging injuries that orthopaedic traumatologists manage. The current knowledge of functional alterations with regard to malreduction of talar fractures is well established. Decision making with regard to timing, approach, and implant selection as well as strategies to help achieve accurate restoration of talar anatomy substantially affect outcomes and must be carefully considered. Perfect anatomic talar reconstruction should always be attempted, and orthopaedic surgeons should have a strong working knowledge of the vascular, three-dimensional, and radiographic anatomy of the talus before performing talar surgery. Almost the entire talus is surgically accessible via several approaches, all of which surgeons should be clinically familiar with to optimize reduction and fixation and safely preserve the soft-tissue envelope. Furthermore, surgeons must appreciate the plantarmedial vascular area of the talus, which must be avoided during dissection. The complication rates in patients who have talar fractures are high, particularly in those who have talar neck and talar body fractures; therefore, patients should be counseled on their expected outcome, with a specific discussion on the risk of osteonecrosis and subtalar arthritis.

The metalation of hen egg white lysozyme impacts protein stability as shown by ion mobility mass spectrometry, differential scanning calorimetry, and X-ray crystallography

Metalation of lysozyme with anticancer organometallics results in protein destabilisation, probably relevant in metallodrug mode of action.

Anticancer activity of Ru- and Os(arene) compounds of a maleimide-functionalized bioactive pyridinecarbothioamide ligand

With the aim of increasing the accumulation of Ru anticancer agents in the tumor, a targeted delivery strategy based on a maleimide anchor for the biological vector human serum albumin (HSA) was developed. A group of piano stool Ru- and Os(η⁶-arene) complexes carrying a maleimide-functionalized N-phenyl-2-pyridinecarbothioamide (PCA) ligand was designed allowing for covalent conjugation to biological thiols. The complexes were characterized by NMR spectroscopy, ESI-MS, elemental analysis and single-crystal X-ray diffraction analysis. The compounds were shown to undergo halido/aqua ligand exchange reactions in aqueous solution, depending mainly on the metal center and the nature of the halide. In vitro cytotoxicity studies revealed low potency which is explained by the observed high reactivity of the maleimide to the thiol of l-cysteine (Cys), while the metal center itself shows little affinity to amino acids of the model protein lysozyme.

A meta-review of stress, coping and interventions in dementia and dementia caregiving

Background

There has been a substantial number of systematic reviews of stress, coping and interventions for people with dementia and their caregivers. This paper provides a meta-review of this literature 1988-2014.

Method

A meta-review was carried out of systematic reviews of stress, coping and interventions for people with dementia and their caregivers, using SCOPUS, Google Scholar and CINAHL Plus databases and manual searches.

Results

The meta-review identified 45 systematic reviews, of which 15 were meta-analyses. Thirty one reviews addressed the effects of interventions and 14 addressed the results of correlational studies of factors associated with stress and coping. Of the 31 systematic reviews dealing with intervention studies, 22 focused on caregivers, 6 focused on people with dementia and 3 addressed both groups. Overall, benefits in terms of psychological measures of mental health and depression were generally found for the use of problem focused coping strategies and acceptance and social-emotional support coping strategies. Poor outcomes were associated with wishful thinking, denial, and avoidance coping strategies. The interventions addressed in the systematic reviews were extremely varied and encompassed Psychosocial, Psychoeducational, Technical, Therapy, Support Groups and Multicomponent interventions. Specific outcome measures used in the primary sources covered by the systematic reviews were also extremely varied but could be grouped into three dimensions, viz., a broad dimension of “Psychological Well-Being v. Psychological Morbidity” and two narrower dimensions of “Knowledge and Coping” and of “Institutionalisation Delay”.

Conclusions

This meta-review supports the conclusion that being a caregiver for people with dementia is associated with psychological stress and physical ill-health. Benefits in terms of mental health and depression were generally found for caregiver coping strategies involving problem focus, acceptance and social-emotional support. Negative outcomes for caregivers were associated with wishful thinking, denial and avoidance coping strategies. Psychosocial and Psychoeducational interventions were beneficial for caregivers and for people with dementia. Support groups, Multicomponent interventions and Joint Engagements by both caregivers and people with dementia were generally found to be beneficial. It was notable that virtually all reviews addressed very general coping strategies for stress broadly considered, rather than in terms of specific remedies for specific sources of stress. Investigation of specific stressors and remedies would seem to be a useful area for future research.

Electronic supplementary material

The online version of this article (doi:10.1186/s12877-016-0280-8) contains supplementary material, which is available to authorized users.

Nanotechnology: current concepts in orthopaedic surgery and future directions

Nanotechnology is the study, production and controlled manipulation of materials with a grain size < 100 nm. At this level, the laws of classical mechanics fall away and those of quantum mechanics take over, resulting in unique behaviour of matter in terms of melting point, conductivity and reactivity. Additionally, and likely more significant, as grain size decreases, the ratio of surface area to volume drastically increases, allowing for greater interaction between implants and the surrounding cellular environment. This favourable increase in surface area plays an important role in mesenchymal cell differentiation and ultimately bone-implant interactions. Basic science and translational research have revealed important potential applications for nanotechnology in orthopaedic surgery, particularly with regard to improving the interaction between implants and host bone. Nanophase materials more closely match the architecture of native trabecular bone, thereby greatly improving the osseo-integration of orthopaedic implants. Nanophase-coated prostheses can also reduce bacterial adhesion more than conventionally surfaced prostheses. Nanophase selenium has shown great promise when used for tumour reconstructions, as has nanophase silver in the management of traumatic wounds. Nanophase silver may significantly improve healing of peripheral nerve injuries, and nanophase gold has powerful anti-inflammatory effects on tendon inflammation. Considerable advances must be made in our understanding of the potential health risks of production, implantation and wear patterns of nanophase devices before they are approved for clinical use. Their potential, however, is considerable, and is likely to benefit us all in the future.

Geriatric fractures about the hip: divergent patterns in the proximal femur, acetabulum, and pelvis

Geriatric acetabular, pelvis, and subtrochanteric femur fractures are poorly understood and rapidly growing clinical problems. The purpose of this study was to describe the epidemiologic trends of these injuries as compared with traditional fragility fractures about the hip. From 1993 to 2010, the Nationwide Inpatient Sample (NIS) recorded more than 600 million Medicare-paid hospital discharges. This retrospective study used the NIS to compare patients with acetabular fractures (n=87,771), pelvic fractures (n=522,831), and subtrochanteric fractures (n=170,872) with patients with traditional hip fractures (intertrochanteric and femoral neck, n=3,495,742) with regard to annual trends over an 18-year period in incidence, length of hospital stay, hospital mortality, transfers from acute care institutions, and hospital charges. Traditional hip fractures peaked in 1996 and declined by 25.7% by 2010. During the same 18-year period, geriatric acetabular fractures increased by 67%, subtrochanteric femur fractures increased by 42%, and pelvic fractures increased by 24%. Hospital charges, when controlling for inflation, increased roughly 50% for all fracture types. Furthermore, transfers from outside acute care hospitals for definitive management stayed elevated for acetabular fractures as compared with traditional hip fractures, suggesting a greater need for tertiary care of acetabular fractures. Geriatric acetabular fractures are rapidly increasing, whereas traditional hip fractures continue to decline. Patients with these injuries are more likely to be transferred from their hospital of presentation to another acute care institution, possibly increasing costs and complications. This is likely related to their complexity and the lack of consensus regarding optimal management.

Megaesophagus in a line of transgenic rats: a model of achalasia

Megaesophagus is defined as the abnormal enlargement or dilatation of the esophagus, characterized by a lack of normal contraction of the esophageal walls. This is called achalasia when associated with reduced or no relaxation of the lower esophageal sphincter (LES). To date, there are few naturally occurring models for this disease. A colony of transgenic (Pvrl3-Cre) rats presented with megaesophagus at 3 to 4 months of age; further breeding studies revealed a prevalence of 90% of transgene-positive animals having megaesophagus. Affected rats could be maintained on a total liquid diet long term and were shown to display the classic features of dilated esophagus, closed lower esophageal sphincter, and abnormal contractions on contrast radiography and fluoroscopy. Histologically, the findings of muscle degeneration, inflammation, and a reduced number of myenteric ganglia in the esophagus combined with ultrastructural lesions of muscle fiber disarray and mitochondrial changes in the striated muscle of these animals closely mimic that seen in the human condition. Muscle contractile studies looking at the response of the lower esophageal sphincter and fundus to electrical field stimulation, sodium nitroprusside, and L-nitro-L-arginine methyl ester also demonstrate the similarity between megaesophagus in the transgenic rats and patients with achalasia. No primary cause for megaesophagus was found, but the close parallel to the human form of the disease, as well as ease of care and manipulation of these rats, makes this a suitable model to better understand the etiology of achalasia as well as study new management and treatment options for this incurable condition.

Spondylopelvic dissociation

Spondylopelvic dissociation is a complex injury pattern resulting in multiplanar instability of the lumbopelvis. These injuries have traditionally been known as "suicide jumper's fractures" and have recently increased in prevalence as a result of under-vehicle explosions seen in the past decade of military conflicts in the Middle East. The hallmarks of spondylopelvic dissociation are bilateral vertical sacral fractures with a horizontal component, resulting in lumbosacral instability in the sagittal and axial planes. Surgical treatment has evolved greatly and both percutaneous and open options are available, with triangular osteosynthesis being the most relied on method of fixation.

Vertebral artery injury and severely displaced odontoid fracture: the case for early reduction

PURPOSE

To report a novel treatment method for vertebral artery occlusion. Vertebral artery injuries have a high association with specific cervical fractures including atlanto-axial fractures, displaced fracture patterns, and transverse foramen fractures. Optimal medical management of the occluded vertebral artery has yet to be determined; however, there is an extremely high complication rate with systemic anticoagulation in these patients. Furthermore, unlike appendicular skeleton fracture-dislocations with vascular injury, there is no clear consensus as to the optimal acute management of the displaced odontoid fracture with or without vertebral artery injury.

METHODS

We report on a severely displaced odontoid fracture that was found to have a vertebral artery injury. Medical records and imaging were reviewed.

RESULTS

An 82-year-old female presented to our hospital with a type IIb odontoid fracture after sustaining a ground-level fall. Pertinent physical exam findings were ecchymosis on the left side of her forehead and posterior cervical pain without neurologic deficits. An MRA showed an occluded left vertebral artery. The patient was placed in early cervical traction and the fracture was reduced within 12 h of presentation. Following surgical stabilization, an MR angiogram showed complete reperfusion of the vertebral artery without intimal tear.

CONCLUSION

To our knowledge, this is the first report of a displaced odontoid fracture in which cervical traction was used to restore the perfusion of the vertebral artery. Cervical traction may obviate the need for systemic anticoagulation and should be considered in patients who have an identifiable compression of the vertebral artery even if neurologically intact.

Heterotopic ossification after central nervous system trauma: A current review

Neurogenic heterotopic ossification (NHO) is a disorder of aberrant bone formation affecting one in five patients sustaining a spinal cord injury or traumatic brain injury. Ectopic bone forms around joints in characteristic patterns, causing pain and limiting movement especially around the hip and elbow. Clinical sequelae of neurogenic heterotopic ossification include urinary tract infection, pressure injuries, pneumonia and poor hygiene, making early diagnosis and treatment clinically compelling. However, diagnosis remains difficult with more investigation needed. Our pathophysiological understanding stems from mechanisms of basic bone formation enhanced by evidence of systemic influences from circulating humor factors and perhaps neurological ones. This increasing understanding guides our implementation of current prophylaxis and treatment including the use of non-steroidal anti-inflammatory drugs, bisphosphonates, radiation therapy and surgery and, importantly, should direct future, more effective ones.

Acute compartment syndrome: obtaining diagnosis, providing treatment, and minimizing medicolegal risk

Acute compartment syndrome (ACS) is a surgical emergency. Diagnosis depends on a high clinical suspicion and an understanding of risk factors, pathophysiology and subtle physical exam findings. The typical high risk scenario for ACS is a male patient younger than 35 years of age, involved in a high energy sport or roadway collision, resulting in a tibial shaft fracture. He will go on to develop acute compartment syndrome of the leg in less than 10 hours and require emergent fasciotomy. Diagnosis of ACS in this patient is primarily a clinical one but can be confirmed with invasive intracompartmental pressure monitoring or non-invasive near infrared spectroscopy (NIRS). Delaying the diagnosis will likely result in some degree of permanent disability and places the surgeon at high risk for litigation. This article reviews the salient features of acute compartment syndrome that should be understood by all orthopaedic residents and surgeons.

Smooth muscle caveolae differentially regulate specific agonist induced bladder contractions

AIMS

Caveolae are cholesterol-rich plasmalemmal microdomains that serve as sites for sequestration of signaling proteins and thus may facilitate, organize, and integrate responses to extracellular stimuli. While previous studies in the bladder have demonstrated alterations in caveolae with particular physiologic or pathologic conditions, little attention has been focused on the functional significance of these organelles. Therefore, the purpose of this study was to investigate the role of caveolae in the modulation of receptor-mediated signal transduction and determine the presence and localization of caveolin proteins in bladder tissue.

METHODS

Contractile responses to physiologic agonists were measured in rat bladder tissue before and after disruption of caveolae achieved by depleting membrane cholesterol with methyl-beta-cyclodextrin. Stimulation with agonists was repeated after caveolae were restored as a result of cholesterol replenishment. RT-PCR, immmunohistochemistry, and Western blotting were used to determine the expression and localization of caveolin mRNA and proteins.

RESULTS

Following caveolae disruption, contractile responses to angiotensin II and serotonin were attenuated, whereas responses to bradykinin and phenylephrine were augmented. Cholesterol replenishment restored responses towards baseline. Carbachol and KCl induced contractions were not affected by caveolae disruption. Ultrastructure analysis confirmed loss of caveolae following cholesterol depletion with cyclodextrin and caveolae restoration following cholesterol replacement. Gene and protein expression of caveolin-1, -2, and -3 was detected in bladder tissue. Immunoreactivity for all three caveolins was observed in smooth muscle cells throughout the bladder.

CONCLUSIONS

The functional effects of cholesterol depletion on specific agonist-induced contractile events and the expression of all three caveolins in bladder smooth muscle support a central role for caveolae in regulation of selective G-protein-coupled receptor signaling pathways in bladder smooth muscle. Thus, caveolae serve to differentially regulate bladder smooth muscle by a stimulus-dependent potentiation or inhibition of bladder contraction.

MRI-derived entorhinal and hippocampal atrophy in incipient and very mild Alzheimer's disease

With high resolution, quantitative magnetic resonance imaging (MRI) techniques, it is now possible to examine alterations in brain anatomy in vivo and to identify regions affected in the earliest stages of Alzheimer's disease (AD). In this study, we compared MRI-derived entorhinal and hippocampal volume in healthy elderly controls, patients who presented at the clinic with cognitive complaints, but did not meet criteria for dementia (non-demented), and patients with very mild AD. The two patient groups differed significantly from controls in entorhinal volume, but not from each other; in contrast, they differed from each other, as well as from controls, in hippocampal volume, with the mild AD cases showing the greatest atrophy. Follow-up clinical evaluations available on 23/28 non-demented patients indicated that 12/23 had converted to AD within 12-77 months from the baseline MRI examination. Converters could be best differentiated from non-converters on the basis of entorhinal, but not hippocampal volume. These data suggest that although both the EC and hippocampal formation degenerate before the onset of overt dementia, EC volume is a better predictor of conversion.

Reduced bone density in androgen-deficient women with acquired immune deficiency syndrome wasting

Women with acquired immune deficiency syndrome wasting are at an increased risk of osteopenia because of low weight, changes in body composition, and hormonal alterations. Although women comprise an increasing proportion of human immunodeficiency virus-infected patients, prior studies have not investigated bone loss in this expanding population of patients. In this study we investigated bone density, bone turnover, and hormonal parameters in 28 women with acquired immune deficiency syndrome wasting and relative androgen deficiency (defined as free testosterone < or =3.0 pg/ml, weight < or =90% ideal body weight, weight loss > or =10% from preillness maximum weight, or weight <100% ideal body weight with weight loss > or =5% from preillness maximum weight). Total body (1.04 +/- 0.08 vs. 1.10 +/- 0.07 g/cm2, human immunodeficiency virus-infected vs. control respectively; P < 0.01), anteroposterior lumbar spine (0.94 +/- 0.12 vs. 1.03 +/- 0.09 g/cm2; P = 0.005), lateral lumbar spine (0.71 +/- 0.14 vs. 0.79 +/- 0.09 g/cm2; P = 0.02), and hip (Ward's triangle; 0.68 +/- 0.14 vs. 0.76 +/- 0.12 g/cm2; P = 0.05) bone density were reduced in the human immunodeficiency virus-infected compared with control subjects. Serum N-telopeptide, a measure of bone resorption, was increased in human immunodeficiency virus-infected patients, compared with control subjects (14.6 +/- 5.8 vs. 11.3 +/- 3.8 nmol/liter bone collagen equivalents, human immunodeficiency virus-infected vs. control respectively; P = 0.03). Although body mass index was similar between the groups, muscle mass was significantly reduced in the human immunodeficiency virus-infected vs. control subjects (16 +/- 4 vs. 21 +/- 4 kg, human immunodeficiency virus-infected vs. control, respectively; P < 0.0001). In univariate regression analysis, muscle mass (r = 0.53; P = 0.004) and estrogen (r = 0.51; P = 0.008), but not free testosterone (r = -0.05, P = 0.81), were strongly associated with lumbar spine bone density in the human immunodeficiency virus-infected patients. The association between muscle mass and bone density remained significant, controlling for body mass index, hormonal status, and age (P = 0.048) in multivariate regression analysis. These data indicate that both hormonal and body composition factors contribute to reduced bone density in women with acquired immune deficiency syndrome wasting. Anabolic strategies to increase muscle mass may be useful to increase bone density among osteopenic women with acquired immune deficiency syndrome wasting.

Penile urethral compression-release maneuver as a non-invasive screening test for diagnosing prostatic obstruction

The purpose of this study was to evaluate the feasibility of using a penile urethral compression and quick release maneuver during urination as a potential non-invasive clinical screening tool in the evaluation of patients with voiding dysfunction and the diagnosis of prostatic obstruction. The penile compression-release maneuver was performed in adult men with symptomatic voiding dysfunction and in asymptomatic normal men by compressing the penile urethra for 2-3 seconds after the initiation of flow and quickly releasing the compression. The penile compression-release index, calculated from the resulting flow rate surge (Q(surge)) and the steady flow rate (Q(surg)-Q(s)/Q(s)), was analyzed with respect to the type of voiding dysfunction. A comprehensive urodynamic study was performed in each patient to determine the presence and severity of prostatic obstruction and to measure detrusor contractility. The penile compression-release indices measured with this maneuver in patients with bladder outlet obstruction (183+/-76%, n = 43) or detrusor instability (157+/-65%, n = 13) were significantly greater than the index observed in non-obstructed patients with normal contractility (67+/-37%, n = 24) or in non-obstructed patients with impaired detrusor contractility (70+/- 32%, n = 10). In asymptomatic younger men who had normal free flow rates (>15 mL/s), the penile compression-release index (55+/-29%, n = 20) was significantly less than that observed in patients with outlet obstruction or detrusor instability. These findings suggest that the magnitude of the flow rate change generated after the penile compression-release maneuver depends on the magnitude of the isometric detrusor contraction developed during penile urethral compression and on the conduit status of the outlet. In patients determined to have poor urinary flow rates, this non-invasive maneuver has been able to differentiate prostatic obstruction associated with normal detrusor contractility from other causes of low urinary flow rates. Despite these encouraging trends, further studies in a larger cohort are required to determine its potential clinical utility as a screening tool for diagnosing prostatic obstruction.

Combination of symptom score, flow rate and prostate volume for predicting bladder outflow obstruction in men with lower urinary tract symptoms

PURPOSE

The severity of lower urinary tract symptoms associated with benign prostatic enlargement correlates poorly with bladder outlet obstruction. Since urodynamic studies are presumed to be relatively complex, invasive and not cost-effective, they are not routinely performed by physicians treating men with lower urinary tract symptoms. As a result, a large number of patients are treated for bladder outlet obstruction when in fact obstruction may not be present. Since other noninvasive methods have not been effective for predicting bladder outlet obstruction, we investigated whether a combination of prostate volume, uroflowmetry and the American Urological Association (AUA) symptom index would be reliable for predicting this condition.

MATERIALS AND METHODS

We prospectively evaluated 204 men with a mean age plus or minus standard deviation of 66.7 +/- 7.5 years who presented with lower urinary tract symptoms. Each patient completed an AUA symptom index questionnaire and underwent uroflowmetry, post-void residual urine volume measurement, pressure flow study and transrectal ultrasound of the prostate to estimate prostatic volume. We constructed receiver operating characteristics curves using various threshold values for maximum urine flow and prostate volume. Threshold values for maximum urine flow and prostate volume were used alone and combined with the AUA symptom index for predicting bladder outlet obstruction. We selected a cutoff value for maximum urine flow of 10 or less ml. per second and prostate volume of 40 gm. or greater, and used these values with an AUA symptom index of greater than 20 to predict bladder outlet obstruction in the group overall.

RESULTS

Differences in the mean symptom index score in men with and without bladder outlet obstruction were not statistically significant. There was no obstruction in 19%, 28.9% and 35% of those with severe, moderate and mild symptoms, respectively. The selected cutoff values of maximum urine flow, prostate volume and symptom score combined correctly predicted obstruction in all 39 patients. Therefore, our combination of cutoff values proved to be highly accurate for predicting bladder outlet obstruction. Sensitivity, specificity, and positive and negative predictive values were 26%, 100%, 100% and 32%, respectively.

CONCLUSIONS

Our study showed that combining the AUA symptom index, maximum urine flow and prostate volume reliably predicted bladder outlet obstruction in a small subset of patients only. Although bladder outlet obstruction was correctly predicted by our threshold values of AUA symptom index, maximum urine flow and prostate volume in only 39 men (26%) with obstruction, these patients represent a substantial group in any large urological practice treating male lower urinary tract symptoms.

Hemispheric differences in hippocampal volume predict verbal and spatial memory performance in patients with Alzheimer's disease

Atrophy of the hippocampal formation, a region important for the acquisition of new declarative knowledge, has been well-documented in Alzheimer's disease (AD), although the relation of such atrophy to the extent of memory dysfunction in these patients has been less clear. In the present study, 18 patients with a clinical diagnosis of probable AD were studied with a high-resolution, quantitative magnetic resonance imaging (MRI) protocol, as well as the verbal and spatial versions of the Buschke controlled learning task. The volumes of the hippocampal formation and, as a control for generalized atrophy, parahippocampal gyrus and temporal neocortex were computed from gapless coronal slices taken perpendicular to the long axis of the hippocampus. To correct for individual differences in brain size, volumes of regions of interest were divided by total intracranial volume. Separate stepwise regression analyses (with age, right and left hippocampal, parahippocampal gyrus, and temporal lobe volumes as the independent variables) showed that left hippocampal volume was the best predictor of free recall and delayed free recall of verbal information (P = 0.0042 and P < 0.0001, respectively). Recall and delayed recall of the spatial location of verbal items were best predicted by right hippocampal volume (P = 0.0054 and P = 0.0118, respectively). Memory scores did not correlate either with parahippocampal gyrus or temporal lobe volume. Furthermore, the relation between hippocampal volume and memory function observed in cases with AD did not hold for healthy aged control subjects.

The maximum watts factor as a measure of detrusor contractility independent of outlet resistance

The maximum watts factor (WFmax) is often used to characterize detrusor contractility. It was recently shown that the WFmax may increase in some patients with chronic outlet obstruction. It is, however, unclear whether this increase reflects a dependence of the WFmax on the degree of outlet obstruction or whether it represents a true increase in detrusor contractility secondary to chronic outlet obstruction. Therefore, this study was performed to investigate this issue using a canine model of acute outlet obstruction. Urodynamic studies were performed on adult canines with surgically exposed lower urinary tracts. Pressure transducers were used to measure the intravesical and the distal urethral pressures, whereas an ultrasonic flow meter was used to obtain a simultaneous measure of the urinary flow rate. Detrusor contractions were induced by electrically stimulating the pelvic nerves bilaterally. Varying degrees of outlet obstruction were created using an inflatable sphincter cuff secured around the bladder outlet. The WFmax, the detrusor pressure at voiding terminus (Pdet.clos), and the passive urethral resistance (R) were computed from measured pressure-flow rate data at each degree of outlet obstruction. The WFmax was not significantly correlated to either the sphincter cuff volume (r = 0.025, p = 0.871), the Pdet.clos (r = 0.286, p = 0.073) or the R (r = 0.110, p = 0.509). The WFmax was not significantly different among mild, moderate, and severe degrees of outlet obstruction (p = 0.176). Our results suggest that the WFmax is independent of the degree of acute outlet obstruction (defined in terms of the sphincter cuff volume, Pdet.clos and R). This validates the current practice of using the WFmax to evaluate detrusor function in patients with voiding dysfunction regardless of outlet resistance. Further, since the WFmax is independent of outlet obstruction acutely, it is reasonable that it would also be independent of outlet obstruction under chronic conditions. Our results, therefore, also imply that the increase in the WFmax with chronic outlet obstruction may represent a true increase in detrusor contractility and not a WFmax dependence on outlet resistance.

Effect of radical prostatectomy on sensory threshold and pressure transmission

PURPOSE

The mechanisms involved in post-radical prostatectomy incontinence remain unclear despite previous anatomical and functional studies. In addition, the factors responsible for the restoration of continence are not well studied. To improve our understanding of the alterations in continence mechanisms, we prospectively investigated the temporal changes in urodynamic parameters after radical prostatectomy.

MATERIALS AND METHODS

Cystometry, urethral pressure profilometry and posterior urethral sensory threshold measurements were performed in patients undergoing radical prostatectomy. Preoperative pressure transmission was determined by the maximal urethral pressure divided by the maximal abdominal pressure during cough maneuvers at a bladder volume of 200 ml. Postoperative sensory threshold, pressure transmission (% of pressure transmission), maximal urethral closure pressure and functional sphincter length were measured 6 weeks and 6 months after prostatectomy. These parameters were compared between continent and incontinent patients.

RESULTS

Preoperative and postoperative urodynamic studies were completed in 34 patients. The continence rate after 6 weeks was 18% (6 patients) and improved to 82% (28) after 6 months. Preoperatively sensory threshold was 16 +/- 11 mA. After 6 weeks and 6 months, respectively, sensory threshold was significantly higher in incontinent (84 +/- 11 mA., 70 +/- 8 mA.) compared to continent (65 +/- 8 mA., 41 +/- 12 mA.) patients. Preoperative proximal urethral sensory threshold was not correlated with degree of postoperative incontinence determined by pad tests. Pressure transmission was not different in continent and incontinent patients postoperatively. After 6 weeks and 6 months, respectively, pressure transmission was 77% and 91% in continent, and 37% and 58% in incontinent patients (p = 0.04, p = 0.03). Maximal urethral closure pressure was significantly higher in continent patients (35 +/- 6 cm. H2O) compared to incontinent patients (11 +/- 9 cm. H2O). Sphincter length decreased from 50 mm. preoperatively to 24 mm. after 6 weeks and 25 mm. after 6 months. There was no difference in sphincter length between continent and incontinent patients.

CONCLUSIONS

Posterior urethral sensitivity and pressure transmission are impaired immediately after prostatectomy. An improvement in these parameters after 6 months is associated with the restoration of continence. These observations suggest that urinary continence after radical prostatectomy depends on the integrity of posterior urethral sensation and the efficiency of pressure transmission.

Characterization of ureteral dysfunction in an experimental model of congenital bladder outlet obstruction

PURPOSE

Ureteral dysfunction is a significant sequela of congenital bladder outlet obstruction. However, the structural and functional alterations associated with ureteral dysfunction are not well defined. A model of fetal bladder obstruction in sheep was used to characterize the changes in ureteral smooth muscle, extracellular matrix (ECM) and functional properties in response to bladder outlet obstruction.

MATERIALS AND METHODS

Partial bladder outlet obstruction was created in fetal sheep at gestational age 95 days via placement of a metal ring around the proximal urethra as well as ligation of the urachus. Ureters were harvested at 109 and 135 days (full term = 140 days) to determine the relative composition of smooth muscle, ECM and urothelium by morphometric analysis and to measure DNA and protein concentrations. Ureteral tissue from 135 day gestation obstructed and control sheep was harvested and immediately placed in Krebs solution. Smooth muscle strips (2-3 mm. x 7-8 mm.) were suspended in organ baths. The frequency and amplitude of spontaneous ureteral contractions was as well as the response to electric field stimulation (EFS) were determined.

RESULTS

Bladder outlet obstruction caused a significant increase in ureteral weight, smooth muscle mass and total ECM at both 109 and 135 days gestation. Total ureteral DNA was greater in obstructed compared with sham ureters at 135 days gestation. Obstructed ureters demonstrated greater amplitude and frequency of spontaneous contractions as well as more pronounced response to EFS when compared to sham ureters.

CONCLUSIONS

The fetal ureter responds to bladder obstruction with smooth muscle hyperplasia and hypertrophy which is associated with increased spontaneous activity and augmented response to EFS. ECM content is markedly increased indicating a shift in the balance of connective tissue synthesis and degradation. Congenital post-obstructive ureteral dysfunction therefore appears to be the result of dysregulated smooth muscle cell growth and altered ECM homeostasis producing abnormal ureteral contractility.

The flow regimes and the pressure-flow relationship in the canine urethra

Classical fluid dynamics predicts that the pressure difference Deltap between any two points along a fully developed, viscous flow stream is linearly proportional to the flow rate Q (the Poiseuille relation). However, the passive urethral resistance relationship (PURR) widely used in modern urodynamics describes the pressure difference Deltap between two points along the urethra as linearly proportional to the flow rate squared (Q(2)). It is our hypothesis that this functional dependence may have its origins in the developing flow field within the urethra. That is, rather than being fully developed hydrodynamically, urethral flow is more likely representative of flow within the entry length of a rigid conduit. In our study, we used a canine model of the lower urinary tract to investigate the possibility of entrance effects. Although the most rigorous model of urethral fluid mechanics would include the elastic properties of the urethra into its configuration, the solutions from such a model would be unnecessarily complex and not readily lend themselves to the analysis of clinical data. Therefore, we chose to model the canine urethra at each instant in time as a rigid tube, and characterized its instantaneous flow using viscous flow theory for a rigid tube. All urodynamic analyses were performed on a surgically exposed urinary tract. Solid state pressure transducers were used to measure the intravesical and distal urethral pressures, whereas an ultrasonic flowmeter was used to obtain a simultaneous measure of the urinary flow rate. Detrusor contractions were induced using bilateral electrical stimulation of the pelvic nerves. Varying degrees of outlet obstruction were created using an inflatable sphincter cuff secured around the bladder outlet. The experimental data were evaluated using the well-known laminar entry length model of Atkinson and Goldstein. The peak Reynolds numbers under nonobstructed R(p)(e non-obs) and obstructed R(p)(e obs) outlet conditions ranged between 500 < R(p)(e non-obs) < 1,500 and 300 < R(p)(e obs) < 1,700, respectively. Under non-obstructed outlet conditions, the urethral diameters D and total lengths l(T) ranged between 1.5 mm < D < 2.5 mm and 75 mm < l(T) < 95 mm, respectively, whereas the peak entrance lengths L(p)(e non-obs) ranged between 55 mm < L(p)(e non-obs) < 215 mm. These data suggest that flow in the canine urethra under both non-obstructed and obstructed outlet conditions is typically laminar. The data further support the hypothesis that non-obstructed flows are predominantly entry length in nature. Entry length flows are fluid dynamically described by a quadratic pressure-flow relationship, thus suggesting a physiological basis for Schäfer's quadratic pressure-flow relationship, and therefore, for the PURR. Neurourol. Urodynam. 18:521-541, 1999.

The functional interaction of visual-perceptual and response mechanisms during selective attention in young adults, young-old adults, and old-old adults

A response compatibility paradigm was employed to address how the perceptual and response activation processes functionally interact during selective attention and how they may be influenced by aging. The results showed that increasing the visual similarity of targets within response sets reduced the magnitude of the interference effect, but only with a narrow interletter distance. In a dissimilar condition, the magnitude of the interference effect did not vary with age. However, in a similar condition, the magnitude of the interference effect was larger for both young (18-30 years) and young-old adults (55-79 years) than for old-old adults (> or = 80 years). In contrast, all three groups showed similar facilitation effects. These results failed to provide support for the notion that enhanced spatial filtering of the target from the flankers produces a corresponding decrease in response competition. Rather, the decrease in the interference effect can be attributed to a functional interaction between the perceptual availability of partial information and the magnitude of response competition. The results also suggest that age does not impair response activation but that advanced age diminishes the availability of local, but not global, feature information.

Urodynamic characterization of nonobstructive voiding dysfunction in symptomatic elderly men

PURPOSE

The pathogenesis of lower urinary tract symptoms in men without bladder outlet obstruction has not been well characterized. Therefore, we defined the urodynamic abnormalities associated with symptomatic nonobstructive voiding dysfunction, and determined the relationship between age and type of dysfunction.

MATERIALS AND METHODS

Video urodynamic studies of symptomatic men without outlet obstruction were examined. The criterion for a normal bladder outlet was a pressure gradient across the prostatic urethra of 5 cm. water or less in the absence of distal stricture. A maximum isometric contraction pressure less than 60 cm. water was regarded as impaired detrusor contractility. Detrusor instability was defined as involuntary detrusor contractions during filling or the inability to suppress a detrusor contraction after initiation of flow. Patients were categorized into 4 groups based on the urodynamic findings.

RESULTS

Of 193 men (mean age 69.6+/-10.5 years) 40.9% had detrusor instability (group 1), 31.1% had impaired contractility (group 2), 10.8% had detrusor instability and impaired contractility (group 3), and 17.1% were urodynamically normal (group 4). Average patient age was significantly lower in group 4 than all other groups. Bladder capacity was lowest in group 1, and group 3 had the lowest voiding efficiency. Maximum flow rate, bladder compliance and symptom scores were not different among the 4 groups. The prevalence of detrusor instability with and without impaired contractility increased, while the proportion of patients without urodynamic abnormalities decreased with age. Bladder contractility did not correlate with age.

CONCLUSIONS

The nonobstructed patient population comprises several groups that are functionally distinct while symptomatically similar. Thus, treatment of nonobstructed cases based on symptoms may lead to inappropriate pharmacological therapy and unsuccessful clinical outcomes.

Role of M2 domain residues in conductance and gating of acetylcholine receptors in developing Xenopus muscle

1. The contributions of specific residues in gamma- and epsilon-subunits to the developmental changes in conductance and open time of Xenopus muscle acetylcholine receptors (AChRs) were investigated. This study was directed primarily at residues in the M2 domains of gamma- and epsilon-subunits; however, the results of additional mutations in the extracellular region flanking M2 and in the amphipathic region between M3 and M4 are also described. 2. The M2 domains of gamma- and epsilon-subunits differ at only three amino acid residues, two of which are adjacent to each other and located near the narrowest part of the pore. These two residues (NI in gamma, SV in epsilon) were found to be major determinants of the difference in conductance and open time of AChRs bearing gamma- or epsilon-subunits. 3. Mutation of N to S in the gamma-subunit converted the long open time of receptors bearing the gamma-subunit (gamma-AChRs) to the brief open time characteristic of receptors bearing an epsilon-subunit (epsilon-AChRs). Conversely, epsilon-AChRs with SV mutated to NI in the epsilon-subunit exhibited a long open time characteristic of gamma-AChRs. 4. Mutation of N to S in the gamma-subunit increased the conductance of gamma-AChRs but did not confer the full conductance of wild-type epsilon-AChRs. Conversely, mutation of SV to NI in the epsilon-subunit reduced the conductance of epsilon-AChRs, but not completely to the level of wild-type gamma-AChRs.