Fractal Electronics for Stimulating and Sensing Neural Networks: Enhanced Electrical, Optical, and Cell Interaction Properties

Imagine a world in which damaged parts of the body - an arm, an eye, and ultimately a region of the brain - can be replaced by artificial implants capable of restoring or even enhancing human performance. The associated improvements in the quality of human life would revolutionize the medical world and produce sweeping changes across society. In this chapter, we discuss several approaches to the fabrication of fractal electronics designed to interface with neural networks. We consider two fundamental functions - stimulating electrical signals in the neural networks and sensing the location of the signals as they pass through the network. Using experiments and simulations, we discuss the favorable electrical performances that arise from adopting fractal rather than traditional Euclidean architectures. We also demonstrate how the fractal architecture induces favorable physical interactions with the cells they interact with, including the ability to direct the growth of neurons and glia to specific regions of the neural-electronic interface.

Fractal Resonance: Can Fractal Geometry Be Used to Optimize the Connectivity of Neurons to Artificial Implants?

In parallel to medical applications, exploring how neurons interact with the artificial interface of implants in the human body can be used to learn about their fundamental behavior. For both fundamental and applied research, it is important to determine the conditions that encourage neurons to maintain their natural behavior during these interactions. Whereas previous biocompatibility studies have focused on the material properties of the neuron-implant interface, here we discuss the concept of fractal resonance - the possibility that favorable connectivity properties might emerge by matching the fractal geometry of the implant surface to that of the neurons.To investigate fractal resonance, we first determine the degree to which neurons are fractal and the impact of this fractality on their functionality. By analyzing three-dimensional images of rat hippocampal neurons, we find that the way their dendrites fork and weave through space is important for generating their fractal-like behavior. By modeling variations in neuron connectivity along with the associated energetic and material costs, we highlight how the neurons' fractal dimension optimizes these constraints. To simulate neuron interactions with implant interfaces, we distort the neuron models away from their natural form by modifying the dendrites' fork and weaving patterns. We find that small deviations can induce large changes in fractal dimension, causing the balance between connectivity and cost to deteriorate rapidly. We propose that implant surfaces should be patterned to match the fractal dimension of the neurons, allowing them to maintain their natural functionality as they interact with the implant.

Using Fractal Iconography to Emulate Nature's Aesthetics

This year's cover artists are members of a team of physicists and psy-chologists who create human-centered designs based on psychology experiments that investigate the positive impacts of viewing fractal patterns. These positive impacts include reduced physiological stress levels and enhanced cognitive skills. Here, the team explores the concept of 'fractal iconography' as an approach to employing computers to generate naturalistic art. Adopting this approach, three forms of fractal patterning ('fractal icons') are combined in a variety of ways to generate the rich complexity of nature's scenery. These composite fractals are remarkably effective at conveying nature's aesthetic power.

Mapping small mammal optimal habitats using satellite-derived proxy variables and species distribution models

Small mammal species play an important role influencing vegetation primary productivity and plant species composition, seed dispersal, soil structure, and as predator and/or prey species. Species which experience population dynamics cycles can, at high population phases, heavily impact agricultural sectors and promote rodent-borne disease transmission. To better understand the drivers behind small mammal distributions and abundances, and how these differ for individual species, it is necessary to characterise landscape variables important for the life cycles of the species in question. In this study, a suite of Earth observation derived metrics quantifying landscape characteristics and dynamics, and in-situ small mammal trapline and transect survey data, are used to generate random forest species distribution models for nine small mammal species for study sites in Narati, China and Sary Mogul, Kyrgyzstan. These species distribution models identify the important landscape proxy variables driving species abundance and distributions, in turn identifying the optimal conditions for each species. The observed relationships differed between species, with the number of landscape proxy variables identified as important for each species ranging from 3 for Microtus gregalis at Sary Mogul, to 26 for Ellobius tancrei at Narati. Results indicate that grasslands were predicted to hold higher abundances of Microtus obscurus, E. tancrei and Marmota baibacina, forest areas hold higher abundances of Myodes centralis and Sorex asper, with mixed forest-grassland boundary areas and areas close to watercourses predicted to hold higher abundances of Apodemus uralensis and Sicista tianshanica. Localised variability in vegetation and wetness conditions, as well as presence of certain habitat types, are also shown to influence these small mammal species abundances. Predictive application of the Random Forest (RF) models identified spatial hot-spots of high abundance, with model validation producing R2 values between 0.670 for M. gregalis transect data at Sary Mogul to 0.939 for E. tancrei transect data at Narati. This enhances previous work whereby optimal habitat was defined simply as presence of a given land cover type, and instead defines optimal habitat via a combination of important landscape dynamic variables, moving from a human-defined to species-defined perspective of optimal habitat. The species distribution models demonstrate differing distributions and abundances of host species across the study areas, utilising the strengths of Earth observation data to improve our understanding of landscape and ecological linkages to small mammal distributions and abundances.

Landscape-scale drivers of pollinator communities may depend on land-use configuration

Research into pollinators in managed landscapes has recently combined approaches of pollination ecology and landscape ecology, because key stressors are likely to interact across wide areas. While laboratory and field experiments are valuable for furthering understanding, studies are required to investigate the interacting drivers of pollinator health and diversity across a broader range of landscapes and a wider array of taxa. Here, we use a network of 96 study landscapes in six topographically diverse regions of Britain, to test the combined importance of honeybee density, insecticide loadings, floral resource availability and habitat diversity to pollinator communities. We also explore the interactions between these drivers and the cover and proximity of semi-natural habitat. We found that among our four drivers, only honeybee density was positively related to wild pollinator abundance and diversity, and the positive association between abundance and floral resources depended on insecticide loadings and habitat diversity. By contrast, our exploratory models including habitat composition metrics revealed a complex suite of interactive effects. These results demonstrate that improving pollinator community composition and health is unlikely to be achieved with general resource enhancements only. Rather, local land-use context should be considered in fine-tuning pollinator management and conservation. This article is part of the theme issue 'Natural processes influencing pollinator health: from chemistry to landscapes'.

A model of the extent and distribution of woody linear features in rural Great Britain

Hedges and lines of trees (woody linear features) are important boundaries that connect and enclose habitats, buffer the effects of land management, and enhance biodiversity in increasingly impoverished landscapes. Despite their acknowledged importance in the wider countryside, they are usually not considered in models of landscape function due to their linear nature and the difficulties of acquiring relevant data about their character, extent, and location. We present a model which uses national datasets to describe the distribution of woody linear features along boundaries in Great Britain. The method can be applied for other boundary types and in other locations around the world across a range of spatial scales where different types of linear feature can be separated using characteristics such as height or width. Satellite‐derived Land Cover Map 2007 (LCM2007) provided the spatial framework for locating linear features and was used to screen out areas unsuitable for their occurrence, that is, offshore, urban, and forest areas. Similarly, Ordnance Survey Land‐Form PANORAMA®, a digital terrain model, was used to screen out where they do not occur. The presence of woody linear features on boundaries was modelled using attributes from a canopy height dataset obtained by subtracting a digital terrain map (DTM) from a digital surface model (DSM). The performance of the model was evaluated against existing woody linear feature data in Countryside Survey across a range of scales. The results indicate that, despite some underestimation, this simple approach may provide valuable information on the extents and locations of woody linear features in the countryside at both local and national scales.

Evolution of self-assembled ZnTe magic-sized nanoclusters

Three families of ZnTe magic-sized nanoclusters (MSNCs) were obtained exclusively using polytellurides as a tellurium precursor in a one-pot reaction by simply varying the reaction temperature and time only. Different ZnTe MSNCs exhibit different self-assembling or aggregation behavior, owing to their different structure, cluster size, and dipole-dipole interactions. The smallest family of ZnTe MSNCs (F323) does not reveal a crystalline structure and as a result assembles into lamellar triangle plates. Continuous heating of as synthesized ZnTe F323 assemblies resulted in the formation of ZnTe F398 MSNCs with wurzite structure and concomitant transformation into lamellar rectangle assemblies with the organization of nanoclusters along the ⟨002⟩ direction. Further annealing of ZnTe F398 assembled lamellar rectangles leads to full organization of MSNCs in all directions and formation of larger ZnTe F444 NCs that spontaneously form ultrathin nanowires following an oriented attachment mechanism. The key step in control over the size distribution of ZnTe ultrathin nanowires is, in fact, the growth mechanism of ZnTe F398 MSNCs; namely, the step growth mechanism enables formation of more uniform nanowires compared to those obtained by continuous growth mechanism. High yield of ZnTe nanowires is achieved as a result of the wurzite structure of F398 precursor. Transient absorption (TA) measurements show that all three families possess ultrafast dynamics of photogenerated electrons, despite their different crystalline structures.

Abstract PD10-03: Predictive value of a proliferation score (MS) in postmenopausal women with endocrine-responsive breast cancer: results from International Breast Cancer Study Group (IBCSG) Trial IX

Background: While representing the largest fraction of women diagnosed with primary breast cancer, older postmenopausal women with ER+, HER2− tumors are less responsive to chemoendocrine therapy than younger women and have been underrepresented in molecular profiling of randomized trials. IBCSG Trial IX, a randomized controlled trial in postmenopausal women, median age 61y, with node negative disease, failed to demonstrate the benefit of preceding tamoxifen (T) by 3 cycles of CMF for ER+ tumors. We sought to determine if MS, a proliferation score, could identify a subset of women who differentially benefit from addition of chemotherapy to T in this trial.

Methods: From 1988–1999, 1669 eligible patients (1040 with ER+, HER2− tumors) were randomized to CMF→T vs T. Disease-free survival (DFS) was the primary trial endpoint; breast cancer-free interval (BCFI) which excludes second (non-breast) malignancies and censors deaths without prior cancer event was also evaluated. Analysis was limited to the first 7 years of follow-up. From 671 (ER+, HER2−) available subjects, 568 were successfully profiled by RT-PCR. The mRNA expression levels of 14 equally-weighted proliferation genes and 3 normalization genes were used to generate MS; predetermined binary categorization of MS was used. Analysis of this post hoc, pre-specified study used results from centralized laboratory IHC and Cox models to assess the predictive value of MS on DFS and BCFI, adjusting for traditional risk factors of local treatment, age, ER, PR, Ki67, tumor size and grade.

Results: Subgroups of MS (low, 169 samples (30%) and high, 399 samples (70%)) were identified. MS by treatment interaction was significant for DFS and BCFI (each p ≤ 0.004). Among patients with low MS, CMF→T improved DFS (HR 0.19, 95% CI 0.06–0.59) and BCFI (HR 0.19, 95% CI 0.05–0.72) vs T; 7y DFS was 95% vs 83% with CMF→T vs T. Among patients with high MS, CMF→T did not improve DFS (HR 1.27, 95% CI 0.79–2.05) or BCFI (HR 1.37, 95% CI 0.80–2.33) and 7y DFS of 81% for CMF→T and T. Continuous MS was moderately correlated with log Ki67 (r = 0.47) but not correlated with ER or PR. The MS by treatment interaction remained significant with Ki67 in the model.

Conclusions: Low MS was associated with differential benefit favoring those women receiving CMF→T vs T alone for both DFS and BCFI in the first 7 years. The effect was independent of traditional risk factors including Ki67. Hence this study, which is unconfounded by chemotherapy-induced ovarian ablation in younger women, identifies a subset of postmenopausal women with ER+, HER2− tumors that benefit from CMF chemotherapy. This seemingly incongruous observation is consistent with a) the prior observation that only the low-proliferation subgroup by PAM50 11-gene signature benefits from the addition of weekly paclitaxel to adjuvant FEC (GEICAM/9906), b) the ability of MS to identify a subset of women with tumors with disseminated luminal progenitor cells activated through the agonistic activity of tamoxifen, and c) the repetitive dosing of cyclophosphamide and taxol being hypothesized to act via tumor stroma/anti-angiogenesis. The relative contribution of these factors is under investigation.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr PD10-03.

Investigating hormonal adaptations to high altitude: five years of Defence Medical Services expeditions

The military has a tradition of supporting and promoting scientific expeditions. The past five years have witnessed a series of Defence Medical Service (DMS) expeditions to mountainous areas of the world, which set out with the dual purpose of researching high altitude human physiology and promoting the uptake of adventurous pursuits within the military. Beginning with exercise Medical Sentinel to Aconcagua, Argentina, in 2007, members of the DMS have since conducted two expeditions to the Himalayas (expedition Imja Tse, 2009 and expedition Khumbu Ramble, 2011) before returning to South America, to the Cordillera Real mountain range in Bolivia, on expedition Bolivian Venture, in late May 2012. This article aims to provide a brief background to the rationale behind these expeditions, a brief description of our understanding of altitude sickness and a history of the adventures that members of the Defence Medical Services have been having contributing to that understanding.

Investigation of fatigue crack growth in acrylic bone cement using the acoustic emission technique

Failure of the bone cement mantle has been implicated in the loosening process of cemented hip stems. Current methods of investigating degradation of the cement mantle in vitro often require sectioning of the sample to confirm failure paths. The present research investigates acoustic emission as a passive experimental method for the assessment of bone cement failure. Damage in bone cement was monitored during four point bending fatigue tests through an analysis of the peak amplitude, duration, rise time (RT) and energy of the events emitted from the damage sections. A difference in AE trends was observed during failure for specimens aged and tested in (i) air and (ii) Ringer's solution at 37 degrees C. It was noted that the acoustic behaviour varied according to applied load level; events of higher duration and RT were emitted during fatigue at lower stresses. A good correlation was observed between crack location and source of acoustic emission, and the nature of the acoustic parameters that were most suited to bone cement failure characterisation was identified. The methodology employed in this study could potentially be used as a pre-clinical assessment tool for the integrity of cemented load bearing implants.

Surgical versus medical treatment for calciphylaxis

Background

Calciphylaxis is a rare, painful, life-threatening problem of cutaneous necrosis and refractory healing seen in patients with uraemia and secondary hyperparathyroidism. The pathogenesis involves abnormalities in calcium and phosphorus metabolism, and acute deposition of calcium in tissues.

Methods

The clinical course of 16 patients diagnosed with calciphylaxis at this institution from 1994 to 1998 was reviewed.

Results

Fourteen women and two men, with a mean age of 56 (range 39–70) years, presented with chronic renal disease of various causes, hyperparathyroidism and characteristic skin lesions. All patients underwent intensive medical therapy, including haemodialysis (n = 16), parathyroidectomy (PTX) (n = 7) and skin debridement of cutaneous lesions (n = 8). Mean preoperative serum values in surgical (PTX) versus non-surgical patients were: calcium 9·9 and 9·3 mg dl−1 (P = 0·25); phosphorus 5·8 and 4·9 mg dl−1 (P = 0·04); calcium–phosphorus product 61·6 and 45·2 (P = 0·03); and parathyroid hormone (PTH) 56·8 and 5·9 pmol l−1 (P = 0·0001) respectively. Mean postoperative values for calcium (8·7 mg dl−1), phosphorus (4·2 mg dl−1), calcium–phosphorus product (30·5) and PTH (4·0 pmol l−1) in surgical patients changed significantly (P < 0·05). Median overall survival was 9·4 months with 15 patients now deceased. Median survival was 14·8 and 6·3 months for PTX versus no PTX (P = 0·22), 14·1 and 6·1 months for skin debridement versus no debridement (P = 0·08), 12·4 and 6·6 months for proximal versus distal skin lesions (P = 0·60), and 6·5 and 13·9 months for diabetic versus non-diabetic patients was (P = 0·11).

Conclusion

Calciphylaxis appears to have a female preponderance with a very dismal prognosis. A multidisciplinary approach using frequent haemodialysis to normalize serum calcium and phosphorus levels, and local debridement of skin lesions seems prudent. PTX cannot be recommended routinely in all such patients unless severe secondary hyperparathyroidism with poorly controlled metabolic disturbance mandates surgery. The exact indications for PTX for calciphylaxis remain unclear.

Primary uncemented total hip arthroplasty in patients <40 years old: 10- to 14-year results using first-generation proximally porous-coated implants

Eighty-two consecutive primary first-generation uncemented total hip arthroplasties (72 patients) performed in patients <40 years old were reviewed with minimum follow-up of 10 years. Of 82 hips, 24 (29.3%) have been revised to date. The estimated survival free of aseptic revision or radiographic failure was 81.3% at 10 years for the acetabular components. The estimated survival free of aseptic revision or radiographic failure was 84.9% at 10 years for the femoral component. In this exclusively young patient cohort, there was a high failure rate of the acetabular component and the femoral component. The data in this report can serve as a baseline for comparison of newer implants and operative methods.

Retention of all-polyethylene acetabular components after femoral revision of a cemented total hip replacement

BACKGROUND

This study was undertaken to provide a basis for decision-making when a well-fixed cemented cup is encountered at the time of a revision of a femoral component of a total hip replacement. It may be beneficial to retain the cup in some instances and thus reduce morbidity, complications, blood loss, operative time, and cost.

METHODS

All patients who had a revision of the femoral component and retention of an all-polyethylene acetabular component from 1971 to 1996 were identified. Three hundred and seventy-four patients with a total of 395 cemented total hip replacements fit the inclusion criteria. The gender, date of and age at the index surgery, type of acetabular implant, and time of and reason for the revision of the femoral component were reviewed. The time to subsequent cup revision or latest surveillance was noted. The average age (and standard deviation) was 66.5 +/- 11.8 years at the time of the femoral revision, which was performed at an average of 8.0 +/- 4.4 years after the primary arthroplasty. For the purposes of this study, the end point for survival of the acetabular component was cup revision for any reason.

RESULTS

At the time of the latest follow-up, at an average of nine years after the femoral revision and 17.3 years after the primary arthroplasty, 342 (86.6%) of the 395 cups remained in situ. Fifty-three cups (13.4%) in fifty-two patients had been revised, at an average of 10.0 +/- 5.7 years after the femoral revision and 16.7 +/- 5.3 years after the primary arthroplasty. The rate of survival of the retained acetabular components was 96.9% at five years, 89.3% at ten years, and 78.7% at fifteen years after the femoral revision and was 95.1% at fifteen years and 87.1% at twenty years after the primary arthroplasty. Increased age (p < 0.0001) and a shorter time-interval (less than 7.5 years) between the primary arthroplasty and the femoral revision (p = 0.05) were significantly associated with an increased likelihood of survival free of cup revision. Femoral head size, acetabular component design, gender, and primary diagnosis did not affect prosthetic survival in this sample of patients.

CONCLUSIONS

The likelihood of survival of the unrevised cup was associated with patient age and duration of implantation, with the age of the patient being the more dominant factor predicting failure of the acetabular component.

Thirty-day mortality after elective total hip arthroplasty

BACKGROUND

Previous reports on perioperative mortality associated with hip arthroplasty have not documented, to our knowledge, patient characteristics and surgical factors that increase the likelihood of death. The purpose of this study was to determine the prevalence of and associated risk factors for perioperative death after elective hip arthroplasty.

METHODS

The records of 30,714 consecutive patients who had undergone elective hip arthroplasty at our institution from 1969 to 1997 were retrospectively reviewed to identify patients who had died within thirty days after the procedure. Mortality rates were determined according to age, gender, diagnosis, implant type, and fixation mode.

RESULTS

Ninety deaths occurred within thirty days after elective total hip arthroplasty, for an overall mortality rate of 0.29% (ninety of 30,714). The thirty-day mortality rate was significantly higher for patients with preexisting cardiovascular disease (p < 0.0001), male patients (p < 0.0001), and patients who were seventy years of age or older (p < 0.0002). The mortality rate was slightly, but not significantly, higher for patients with an underlying diagnosis of rheumatoid arthritis (p < 0.36) and those receiving cemented implants (p < 0.57). There was no difference in the thirty-day mortality rate for revision as compared with primary hip arthroplasty (p < 0.92).

CONCLUSIONS

Factors that are associated with an increased risk of mortality within thirty days after elective hip arthroplasty include an older age, male gender, and a history of cardiorespiratory disease. There has been a significant decline in the thirty-day mortality rate after elective hip arthroplasty in the last decade (p < 0.0002); during the 1990s, the overall rate at our institution was 0.15% (twenty-three of 14,989).

Adrenocortical carcinoma: surgical progress or status quo?

HYPOTHESIS

Outcome of patients with adrenocortical carcinoma (ACC) has improved with the advent of more widely available and higher quality imaging. Operative management strategies and use of adjuvant therapy have not changed.

DESIGN

Retrospective review of patient histories, imaging studies, operative data, adjuvant therapy, and outcomes at a single institution. Follow-up was complete for a mean of 53 months. Data was compared with prior institutional experience.

SETTING

Tertiary care referral center.

PATIENTS

All patients undergoing operative management for ACC during the period from 1980 to 1996.

MAIN OUTCOME MEASURES

Determinants of recurrence, survival, and the effect of adjuvant therapy on overall outcome.

RESULTS

Fifty-eight patients (30 men, 28 women) with a mean age of 53 years underwent primary operative management for ACC. Functional tumors were identified in 27 patients (47%). Mean tumor size was 12.5 cm. Stage according to the TNM staging system (AJCC Cancer Staging Manual) at presentation was I (n = 0), II (n = 30), III (n = 7), and IV (n = 21). Surgical management included curative resection in 41 (71%), noncurative resection in 14 (24%), and open biopsy in 3 (5%). Perioperative mortality was 5%. Recurrence occurred in 30 patients (73%) with a median time to recurrence of 17 months. Five-year survival by the Kaplan-Meier method was 37%. Prognostic factors (P<.05) included functional status, stage, and chemotherapy in stage III/IV patients. When compared with our prior institutional experience (1960-1980), current patients were more likely to present with stages I to II (52% vs. 34%), have curative resections (71% vs. 50%), and have improved 5-year survival (37% vs. 16%).

CONCLUSIONS

(1) Surgical resection remains the principal treatment for stage I to III disease. (2) Adjuvant therapy may improve survival in patients with stage III or IV disease. (3) Current patients were more likely to present at an earlier stage, undergo curative resections, and have improved 5-year survival than institutional historical comparisons.

Assembly of very low density lipoproteins in mouse liver: evidence of heterogeneity of particle density in the Golgi apparatus

The assembly of very low density lipoproteins (VLDL) by hepatocytes is believed to occur via a two-step process. The first step is the formation of a dense phospholipid and protein-rich particle that is believed to be converted to VLDL by the addition of bulk triglyceride in a second step. Previous studies in our laboratory led us to hypothesize a third assembly step that occurs in route to or in the Golgi apparatus. To investigate this hypothesis, nascent lipoproteins were recovered from Golgi apparatus-rich fractions isolated from mouse liver. The Golgi fractions were enriched 125-fold in galactosyltransferase and contained lipoprotein particles averaging approximately 35 nm in diameter. These lipoproteins were separated by ultracentrifugation into two fractions: d < 1.006 g/ml and d1.006;-1.210 g/ml. The d < 1.006 g/ml fraction contained apolipoprotein B-100 (apoB-100), apoB-48, and apoE, while the d1.006;-1.210 g/ml fraction contained these three apoproteins as well as apoA-I and apoA-IV. Both fractions contained a 21-kDa protein that was isolated and sequenced and identified as major urinary protein. Approximately 50% of the apoB was recovered with the denser fraction. To determine if these small, dense lipoproteins were secreted without further addition of lipid, mice were injected with Triton WR1339 and [(3)H]leucine, and the secretion of apoB-100 and apoB-48 into serum VLDL (d < 1.006 g/ml) and d1.006;-1.210 g/ml fractions was monitored over a 2-h period. More than 80% of the newly synthesized apoB-48 and nearly 100% of the apoB-100 were secreted with VLDL. These studies provide the first characterization of nascent lipoproteins recovered from the Golgi apparatus of mouse liver. We conclude that these nascent hepatic Golgi lipoproteins represent a heterogeneous population of particles including VLDL as well as a population of small, dense lipoproteins. The finding of the latter particles, coupled with the demonstration that the primary secretory product of mouse liver is VLDL, suggests that lipid may be added to nascent lipoproteins within the Golgi apparatus.

Is calciphylaxis best treated surgically or medically?

BACKGROUND

Calciphylaxis is a rare, painful, life-threatening problem of cutaneous necrosis and refractory healing in patients with uremia and secondary hyperparathyroidism. The pathogenesis involves abnormalities in calcium and phosphorus metabolism and acute deposition of calcium in tissues.

METHOD

The clinical course of 16 patients who were diagnosed with calciphylaxis at our institution from 1994 through 1998 was reviewed.

RESULTS

Fourteen female patients and 2 male patients had chronic renal disease, secondary hyperparathyroidism, and characteristic skin necrosis (mean age, 56 years; range, 39-70 years). All patients underwent intensive medical therapy, including ongoing hemodialysis (n = 16 patients), parathyroidectomy (n = 7 patients), and debridement of cutaneous lesions (n = 8 patients). Mean serum values in surgical and nonsurgical patients were significantly different for phosphorus, calcium-phosphorus product, and parathormone levels. Median survival was 9.4 months; 15 patients (93%) have died. The median survival time for parathyroidectomy versus nonparathyroidectomy was 14.8 and 6.3 months (P =.22), for skin debridement versus nondebridement was 14.1 and 6.1 months (P =.08), and for diabetic versus nondiabetic patients was 6.5 and 13.9 months (P =.11).

CONCLUSIONS

Calciphylaxis has a female preponderance, with a dismal prognosis. A multidisciplinary approach that uses frequent hemodialysis to normalize calcium and phosphorus levels and local debridement of skin lesions seems prudent. Parathyroidectomy cannot be recommended routinely in all patients, unless severe hyperparathyroidism mandates intervention.

Surgical treatment of adult primary hepatic sarcoma

BACKGROUND

Primary sarcomas of the liver are extremely rare in adults. Optimal therapeutic approaches remain unclear.

METHODS

Twenty consecutive adult patients who had surgical treatment for primary hepatic sarcomas were reviewed. Patient age ranged from 23 to 80 years. Other than one patient with primary hepatic angiosarcoma who had a history of thorium dioxide colloid (Thorotrast) exposure 23 years before diagnosis, no predisposing causes were apparent. Nineteen patients had hepatic resection and one patient had an orthotopic liver transplant. No patient received neoadjuvant chemotherapy or radiotherapy but radiotherapy was delivered intraoperatively in one patient.

RESULTS

Leiomyosarcoma was the most common histological type of sarcoma diagnosed (five of 20 patients), followed by malignant solitary fibrous tumour (four) and epithelioid haemangioendothelioma (three). Fourteen tumours were high-grade sarcomas and six were low grade malignancies. Thirteen patients developed a recurrence. Distant metastases (ten patients) and intrahepatic recurrence (six) were the predominant sites of initial treatment failure. Six patients received salvage chemotherapy. Histological grade was the only factor significantly associated with overall patient survival (P= 0.03). With complete resection, patients with high-grade tumours had a 5-year survival rate of 18 (95 per cent confidence interval 5-62) per cent compared with 80 (52-100) per cent for patients with low-grade tumours. The 5-year survival rate for all 20 patients was 37 (20-60) per cent.

CONCLUSION

Surgical resection is the only effective therapy for primary hepatic sarcomas at present. Better adjuvant therapy is necessary, especially for high-grade malignancies, owing to the high failure rate with operation alone.

Effects of transdermal nicotine treatment on structure and function of coronary artery bypass grafts

Smoking is a major risk factor for failure of coronary artery bypass grafts (CABG). Experiments were designed to determine effects of transdermal nicotine, independent of smoking, on structure and function of CABG. Saphenous veins were placed as CABG in untreated dogs (control) or in dogs treated with transdermal nicotine (one 11-mg or two 22-mg patches/day) for 5 wk. Serum nicotine and plasma nitric oxide were measured. Grafts were removed and prepared for organ chamber studies and histology. Serum nicotine averaged 12.1 and 118.7 ng/ml in the 11 mg/day and 44 mg/day groups, respectively. Plasma nitric oxide was higher in dogs treated with 11 mg/day doses compared with controls. In organ chamber studies, endothelium-dependent relaxations to thrombin and A-23187 and endothelium-independent relaxations to nitric oxide were greatest in grafts from dogs treated with 11 mg/day doses. Intimal thickness of the grafts were similar among groups. However, staining for bone sialoprotein was increased in the media of grafts from the 11 mg/day treatment group. These data suggest that transdermal nicotine in doses comparable and double to those used for conventional smoking cessation treatment in humans does not adversely affect early patency of canine CABG up to 4 wk postoperatively. Transdermal nicotine, however, may increase production of and response to nitric oxide in bypass grafts.

The impact of antidepressant use on social functioning: reboxetine versus fluoxetine

Depression compromises affected individuals' functional well-being and impairs their level of social and workplace performance. Improved social functioning in depressed patients may improve their work productivity. This study evaluated the differential effects of two antidepressants on social functioning outcomes for patients with major depression comparing reboxetine, a non-tricyclic, selective noradrenaline reuptake inhibitor and fluoxetine, a commonly prescribed selective serotonin reuptake inhibitor. A model using data from 284 depressed patients (138 reboxetine, 146 fluoxetine) in two 8-week clinical trials was developed to predict the percentage change over time in continuous outcome assessments as measured by a 21-item self-rating scale called the Social Adaptation Self-evaluation Scale (SASS). The percentage change from baseline SASS score was modelled as a function of both time-invariant and time-varying covariates. Results suggest that, by mid-study, the more severely ill subjects benefitted more from reboxetine treatment in terms of the outcome improvement rate and, by study-end, this effect also extended into the less severely ill population. In addition, a significant relationship was identified between the change in depression symptom severity as measured by the standard Hamilton Depression Rating Scale score and the change in social functioning per the SASS.

Thermal balloon and rollerball ablation to treat menorrhagia: two-year results of a multicenter, prospective, randomized, clinical trial

STUDY OBJECTIVE

To evaluate 2-year follow-up results in patients participating in a randomized, clinical trial comparing uterine balloon therapy with rollerball endometrial ablation.

STUDY DESIGN

Prospective, randomized, clinical trial (Canadian Task Force classification I).

SETTING

Fourteen university-affiliated and private practice sites.

PATIENTS

Two hundred fifty-five women with menorrhagia.

INTERVENTIONS

Patients were randomized to rollerball or uterine balloon endometrial ablation.

MEASUREMENTS AND MAIN RESULTS

Patient satisfaction with both treatments was consistently high. Only 15 hysterectomies had been performed (6 for menorrhagia) at the end of 2 years, 11 in the rollerball group, 4 in the balloon therapy group.

CONCLUSION

Endometrial ablation by both procedures was highly successful in avoiding hysterectomy and relieving symptoms of menorrhagia. Additional benefits were reduction in dysmenorrhea and premenstrual syndrome.

Treatment of invasive thymoma with single-agent ifosfamide

PURPOSE

To evaluate single-agent ifosfamide in the treatment of invasive thymoma.

PATIENTS AND METHODS

Fifteen patients (eight male and seven female) with histologically confirmed invasive thymoma were treated. The median age was 48 years (range, 23 to 76 years). Four patients had stage III disease, seven patients had stage IVa disease, and four patients had stage IVb disease. The most common histologic type was lymphoepithelial. Seven patients had received prior treatment, including one patient who received chemotherapy. Ifosfamide 1.5 g/m(2) was given on days 1 to 5, with mesna as a uroprotector.

RESULTS

Thirteen patients were assessable for response. Five complete responses (38.5%; 95% confidence interval [CI], 17.7% to 64.5%) and one partial response (7.7%; 95% CI, 1.4% to 33.3%) were seen. The median duration of complete response was 66+ months (range, 25 to 87 months), and the estimated survival rate 5 years after ifosfamide treatment was 57% (SE, 32% to 79%). The most frequent toxicities were nausea, vomiting, and leucopenia, but these were well tolerated.

CONCLUSION

Single-agent ifosfamide possesses significant activity against invasive thymoma and is comparable to currently used combination regimens. The inclusion of ifosfamide in combination therapy, particularly in place of cyclophosphamide in regimens such as cisplatin, doxorubicin, and cyclophosphamide, needs to be evaluated.

Use of parents, sibs, and unrelated controls for detection of associations between genetic markers and disease

Detecting the association between genetic markers and complex diseases can be a critical first step toward identification of the genetic basis of disease. Misleading associations can be avoided by choosing as controls the parents of diseased cases, but the availability of parents often limits this design to early-onset disease. Alternatively, sib controls offer a valid design. A general multivariate score statistic is presented, to detect the association between a multiallelic genetic marker locus and affection status; this general approach is applicable to designs that use parents as controls, sibs as controls, or even unrelated controls whose genotypes do not fit Hardy-Weinberg proportions or that pool any combination of these different designs. The benefit of this multivariate score statistic is that it will tend to be the most powerful method when multiple marker alleles are associated with affection status. To plan these types of studies, we present methods to compute sample size and power, allowing for varying sibship sizes, ascertainment criteria, and genetic models of risk. The results indicate that sib controls have less power than parental controls and that the power of sib controls can be increased by increasing either the number of affected sibs per sibship or the number of unaffected control sibs. The sample-size results indicate that the use of sib controls to test for associations, by use of either a single-marker locus or a genomewide screen, will be feasible for markers that have a dominant effect and for common alleles having a recessive effect. The results presented will be useful for investigators planning studies using sibs as controls.

Cost effectiveness of pramipexole in Parkinson's disease in the US

OBJECTIVE

Pramipexole was recently approved in the US for treatment of the symptoms of idiopathic Parkinson's disease (PD). Although pramipexole has been found to be safe and efficacious when compared with placebo, little data are yet available on its cost effectiveness when compared with baseline treatment. The aim of this study was to estimate the costs and cost effectiveness (cost utility) of pramipexole compared with baseline treatment in patients with early and advanced PD.

DESIGN AND SETTING

We developed a cost-effectiveness (CE) model in the US setting that linked Unified Parkinson's Disease Rating Scale (UPDRS) Part II (activities of daily life) and III (motor) scores to disease progression, costs and patient utility. Data for the model were obtained from clinical trials, a literature review and a survey of 193 patients' health resource use and utility. We used cost and quality-adjusted life-year (QALY) estimates from the model to estimate the incremental cost effectiveness of pramipexole relative to baseline treatment patterns. We performed separate analyses for patients with early and advanced PD. We also performed extensive sensitivity analyses by adding other dopamine agonists to the no-pramipexole treatment regimen and varying disease progression parameters. The study was conducted from the societal perspective, although data presentation allows interpretation of cost effectiveness from either the societal or payer perspective.

MAIN OUTCOME MEASURES AND RESULTS

For patients with both early and advanced PD, treatment with pramipexole had higher costs but was more effective than baseline treatment. For patients with early onset of PD, the incremental total CE ratio for pramipexole was $US8837/QALY. For patients with advanced PD, the incremental CE ratio was $US12 294/QALY (1997 costs). These ratios were lower than the CE ratios of many widely used medical treatments.

CONCLUSIONS

Subject to the inherent limitations of modelling chronic disease progression and subsequent healthcare costs and patient utility, the results suggested that pramipexole was a cost effective treatment for patients with early and advanced PD in the US.

Surgical management of intrahepatic cholangiocarcinoma: a 31-year experience

Intrahepatic cholangiocarcinoma (ICC) is the second most common malignant primary tumor of the liver. It is, though, a rare tumor and little is known regarding its natural history, clinicopathologic characteristics, or the outcomes of surgical therapy. We reviewed the experience of 61 patients with ICC seen by the surgical service at the Mayo Clinic over a 31-year period. Patient demographic and clinical data were recorded, as were survival statistics. Pathologic data were also obtained and patients stratified according to the TNM classification. Twenty-eight patients were resected for cure. Overall, 45 patients died of ICC. Of the patients resected for cure, survival at 3 years was 60%. No pathologic condition was found to be associated with the development of ICC. Overall survival correlated with stage of the tumor. Among patients resected for cure, stage did not correlate with survival. Prognosis for patients with ICC remains poor; resection, though, appears to prolong survival.

Quality of life and pharmaco-economic aspects of obsessive-compulsive disorder. A South African survey

OBJECTIVE

The quality of life and pharmaco-economic aspects of obsessive-compulsive disorder (OCD) have received relatively little research attention to date. We aimed to gather preliminary data on these in a South African patient sample.

DESIGN

A survey of members of the Obsessive-Compulsive Disorder Association of South Africa was undertaken by means of a detailed self-report questionnaire.

RESULTS

Results of the survey suggest that OCD causes significant morbidity, leading to clear distress and Interference with academic, occupational, social and family function. Unfortunately, correct diagnosis and appropriate treatment have been delayed in many patients, and the financial costs of such incorrect management are likely to be considerable.

CONCLUSION

Much further work needs to be done by the medical profession and by interested consumers to raise awareness about OCD and to provide information about its management. In South Africa, it is particularly Important to undertake such psycho-education at a primary health care level and to impact on patients of low socio-economic status.

The impact on unemployment of an intervention to increase recognition of previously untreated anxiety among primary care physicians

Anxiety is a common, though often unrecognized, problem in primary care settings. This study examines the effect on employment of an intervention designed to attune primary care physicians to previously unrecognized and untreated anxiety. Primary care physicians in a mixed-model health maintenance organization (HMO) were randomized by practice site to groups with (intervention) and without (usual care) intensive one-on-one education about anxiety and periodic feedback about their patients with anxiety. All persons 21-65 years of age presenting to the offices of these primary care providers were screened for anxiety with the SCL-90-R on two occasions. Those meeting the SCL-90-R cutpoints for anxiety and whose medical records provided no evidence of recognition or treatment for a mental health condition within the last 6 months were eligible for the study (n = 637). Of these, 573 (90%) completed two follow-up assessments. The present study evaluates the impact of the intervention aimed at the primary care physicians on the labor force participation rate of the persons with anxiety after 5 months of follow-up. The study also evaluates the impact of the intervention on hours of work and the presence of days spent in bed among the persons with anxiety working at the baseline interview and after 5 months. At baseline, the patients of intervention and usual care physicians with previously unrecognized and untreated anxiety did not differ in labor force participation rates. At the conclusion of the study, the patients of the intervention group physicians had significantly lower rates of labor force participation than those of the usual care group physicians. Among those working both at the beginning and conclusion of the study, the intervention had no impact on hours of work or the presence of days spent in bed. We conclude that attuning physicians may reduce labor force participation rates.

Hygienic hand disinfection tests in three laboratories

A comparative study was made in three laboratories of a test for hygienic hand disinfection. Staphylococcus aureus was applied to the fingertips of a total of 74 volunteers (49 female and 25 male) and the effect of washing with three chlorhexidine preparations and one non-medicated soap was assessed after one and five applications. Fingertip inoculation is convenient and is a realistic representation of the in-use situation. Although significant differences were obtained between log10 reductions in test organisms using the same formulation in different centres, and different periods in the same centre, the maximum differences after a single application of a preparation were small, e.g. between centres 0.39 and between periods in the same centre 0.55, and after multiple applications the maximum difference between centres was 0.42 and between periods in the same centre it was 0.51. The differences between preparations were similar in all centres. This test compares well with other similar tests and products can be placed in rank order of effectiveness. It is concluded that this test, if carried out under the controlled conditions described, is sufficiently reproducible between laboratories and repeatable within laboratories to be used as a standard test.

Application of the hygienic hand-disinfection test to the gloved hand

The Austrian Standard Hygienic Hand-Disinfection Test was adapted for comparing the effect of washing artificially contaminated hands (using Escherichia coli) with contaminated gloved hands, using liquid soap and rinsing with water. Tests showed that a single soap wash completely removed all the bacteria from the glove, and was more than 1000 times more effective on the glove than on the hand.

Studies on perioperative skin flora

Chlorhexidine in spirit is used to reduce the skin bacterial load before surgery; and recently prewashing with chlorhexidine scrub has been advocated. We describe three studies on cardio-thoracic surgical patients--particularly those having coronary artery grafts with long leg and sternal wounds. Two studies compared prewashes with chlorhexidine scrub (Hibiscrub-ICI) or soap. Study Number One (250 patients per group) was of wound infections; and Number Two (25 patients per group) was of alterations in skin flora for 10 days postoperation. Chlorhexidine scrub failed to reduce overall wound infection rates in Study 1, although leg wounds healed more quickly with less inflammation. Study Two showed that the scrub had a significant effect on skin flora that lasted at least 3 days postoperation. Study Number Three was of 100 patients (no chlorhexidine scrub) examined for methicillin-resistant coagulase-negative staphylococci (MRSE) by cultures of swabs from the leg, sternum and chest drain site before and after operation on methicillin agar. Three per cent of patients had MRSE preoperation (1 doctor) and 23% postoperation. One thousand strains were tested by agar dilution against methicillin and chlorhexidine. MRSE had a 2-8-fold increased resistance to chlorhexidine compared to a greater than 256-fold to methicillin. Thus although chlorhexidine has a marked persistent effect on skin flora, emergence of major resistance is unlikely. Use of postoperative chlorhexidine should be investigated further.

What is in the surgeon's glove?

Three aspects of surgical hand hygiene have been studied: the attitude of the surgeon, the microbiology of glove changing during an operation, and the use of antiseptic-coated gloves together with different handwash routines. The survey revealed that the predominant factor in choice of agent for surgical hand hygiene was skin tolerance. The microbiological studies showed that 'closed' glove changing was to be preferred to 'open' changing, and that antiseptic-coated gloves further suppressed the skin flora, even after prolonged operations, compared to standard gloves.

Multicenter study of trilostane: a new hormonal agent in advanced postmenopausal breast cancer

Trilostane, an inhibitor of the production of adrenal estrogens, was administered, together with dexamethasone, to 97 eligible postmenopausal women with advanced breast cancer. Seventy-four patients who had either received trilostane for a minimum of 10 weeks or whose disease had progressed while on trilostane before this period were assessed for tumour response. Eighteen patients (25%) had objective responses (two complete, 16 partial); a further 21 patients had stable disease. The response rate among all 97 patients, including those not treated for a minimum 10-week period, was 19%. Thirty-two of 97 patients reported adverse reactions which were attributed to trilostane and/or dexamethasone. Therapy was stopped for 15 patients, and the dose of trilostane was reduced for ten. Diarrhea was the commonest side effect, being reported in 16 patients, of whom nine stopped treatment. Trilostane, given with a corticosteroid, is an effective alternative hormonal agent acting by adrenal blockade for postmenopausal women with advanced breast cancer.

Cost-benefit analysis: a research tool for evaluating innovative health programs

This article reviews the evaluation methodology known as cost-benefit analysis. Studies which have utilized this technique are presented and briefly reviewed. In addition, the closely related technique known as cost-effectiveness (C-E) analysis is described and contrasted with cost-benefit analysis. Several research articles utilizing C-E are described. It is recommended that cost-benefit analysis be used as a mechanism to evaluate innovative health programs. This may be the sole mechanism that will enable health practitioners to cost-justify their innovative services to the federal government and other third-party payers.

Individualizing gentamicin dosage regimens in burn patients with gram-negative septicemia: a cost--benefit analysis

Services provided by a clinical pharmacokinetics laboratory were evaluated in terms of an accepted cost--benefit model, and a model to evaluate clinical services provided by the pharmacist is presented. A retrospective study was conducted to evaluate the impact, in terms of patient outcomes, of individualizing gentamicin dosage regimens in severely burned patients. Analysis was conducted using multivariate statistical techniques and appropriate nonparametric and parametric tests to determine significant differences. This analysis provided the necessary data to quantify the impact of the pharmacokinetic service. The findings suggest that significant differences do exist in comparing individually dosed patients against those who were not, based upon discriminant and multiple regression analyses and/or nonparametric tests. Furthermore, the results will be useful for insurance companies, third-party payers, and government agencies in deciding which innovative clinical services should be reimbursed.

Cost of individualizing aminoglycoside dosage regimens

The estimated annual costs associated with operating a clinical pharmacokinetics service within a 450-bed, metropolitan county hospital were studied. Using three aminoglycoside serum level determinations, a computer program estimates the patient's pharmacokinetic variables and calculates a dosage regimen which will maintain serum concentrations in the desired range. Pharmacists are involved in assessing the patient's initial clinical condition and in recommending doses and dosing intervals. Fixed costs included the costs of the physical facility and office equipment ($778/yr). Operating costs included salaries, equipment leasing fees, journal subscription fees and medical supplies ($73,915/yr). The estimated cost per blood sample analyzed for aminoglycoside content was $17.35/sample (4,305 samples/yr). The study provides a basis for comparing the cost of operating a pharmacokinetics service with the cost of other innovative pharmaceutical services.