Artificial Intelligence: Singularity Approaches

SUMMARY

Artificial intelligence (AI) has been a disruptive technology within health care, from the development of simple care algorithms to complex deep-learning models. AI has the potential to reduce the burden of administrative tasks, advance clinical decision-making, and improve patient outcomes. Unlocking the full potential of AI requires the analysis of vast quantities of clinical information. Although AI holds tremendous promise, widespread adoption within plastic surgery remains limited. Understanding the basics is essential for plastic surgeons to evaluate the potential uses of AI. This review provides an introduction of AI, including the history of AI, key concepts, applications of AI in plastic surgery, and future implications.

Vascularized Denervated Muscle Targets for Headache Surgery-Presentation and Surgical Management

Patients with substantial trauma to their occipital nerves and those with recurrent or persistent chronic headaches after occipital nerve decompression surgery require transection of their greater occipital and/or lesser occipital nerves to control debilitating pain. Current techniques, such as burying the transected nerve stump in nearby muscle, do not prevent neuroma formation, and more advanced techniques, such as targeted muscle reinnervation and regenerative peripheral nerve interface, have demonstrated only short-term anecdotal success in the context of headache surgery. Vascularized denervated muscle targets (VDMTs) are a novel technique to address the proximal nerve stump after nerve transection that has shown promise to improve chronic nerve pain and prevent neuroma formation. However, VDMTs have not been described in the context of headache surgery. Here authors describe the etiology, workup, and surgical management of 2 patients with recurrent occipital neuralgia who developed vexing neuromas after previous surgery and were successfully treated with VDMTs, remaining pain-free at 3-year follow-up.

Treatment of Persistent Post-traumatic Diplopia - An Algorithmic Approach to Patient Stratification and Operative Management

Study Design

Retrospective chart review of revisional orbital surgery outcomes in patients with diplopia from prior operative treatment of orbital trauma.

Objective

Our study seeks to review our experience with management of persistent post-traumatic diplopia in patients with previous orbital reconstruction and present a novel patient stratification algorithm predictive of improved outcomes.

Methods

A retrospective chart review was performed on adult patients at Wilmer Eye Institute at Johns Hopkins Hospital and at the University of Maryland Medical Center who underwent revisional orbital surgery for correction of diplopia for the years 2005-2020. Restrictive strabismus was determined by Lancaster red-green testing coupled with computed tomography and/or forced duction. Globe position was assessed by computed tomography. Seventeen patients requiring operative intervention according to study criteria were identified.

Results

Globe malposition affected fourteen patients and restrictive strabismus affected eleven patients. In this select group, improvement in diplopia occurred in 85.7% of cases with globe malposition and in 90.1% of cases with restrictive strabismus. One patient underwent additional strabismus surgery subsequent to orbital repair.

Conclusions

Post-traumatic diplopia in patients with prior orbital reconstruction can be successfully managed in appropriate patients with a high degree of success. Indications for surgical management include (1) globe malposition and (2) restrictive strabismus. High resolution computer tomography and Lancaster red-green testing discriminate these from other causes that are unlikely to benefit from orbital surgery.

Cybersecurity and Technical Patient Privacy Protection

Plastic surgery offices are subject to a wide variety of cybersecurity threats, including ransomware attacks that encrypt the plastic surgeon's information and make it unusable, as well as data theft and disclosure attacks that threaten to disclose confidential patient information. Cloud-based office systems increase the attack surface and do not mitigate the effects of breaches that can result in theft of credentials. Although employee education is often recommended to avoid the threats, a single error by a single employee has often led to security breaches, and it is not reasonable to expect that no employee will ever make an error. A recognition of the two most common vectors of these breaches, compromised email attachments and surfing to compromised websites, allows the use of technical networking tools to both prevent email attachments from being received and to prevent employee use of unsanctioned and potentially compromised websites. Further, once compromised code is allowed to run within the office network, that code must necessarily make outbound connections to exploit the breach. Preventing that outbound traffic can mitigate the effects of a breach. However, most small office network consultants design firewalls to only limit incoming network traffic and fail to implement technical measures to stop the unauthorized outbound traffic that is necessary for most network attacks. Detailed techniques are provided which can be used to direct IT consultants to properly limit outbound network traffic as well as incoming email attachments, with more information at https://officenetworksecurity.com.

Colonizing microbiota is associated with clinical outcomes in diabetic wound healing

With the development of society and the improvement of life quality, more than 500 million people are affected by diabetes. More than 10 % of people with diabetes will suffer from diabetic wounds, and 80 % of diabetic wounds will reoccur, so the development of new diabetic wound treatments is of great importance. The development of skin microbe research technology has gradually drawn people's attention to the complex relationship between microbes and diabetic wounds. Many studies have shown that skin microbes are associated with the outcome of diabetic wounds and can even be used as one of the indicators of wound prognosis. Skin microbes have also been found to have the potential to treat diabetic wounds. The wound colonization of different bacteria can exert opposing therapeutic effects. It is necessary to fully understand the skin microbes in diabetic wounds, which can provide valuable guidance for clinical diabetic wound treatment.

A nanofiber-hydrogel composite improves tissue repair in a rat model of Crohn's disease perianal fistulas

Perianal fistulas (PAFs) represent a severe complication of Crohn's disease (CD). Despite the advent of biologic and small-molecule therapeutics for luminal disease, PAFs in CD (CD-PAF) are relatively resistant to treatment, with less than 50% responding to any therapy. We report an injectable, biodegradable, mechanically fragmented nanofiber-hydrogel composite (mfNHC) loaded with adipose-derived stem cells (ADSCs) for the treatment of fistulas in a rat model of CD-PAF. The ADSC-loaded mfNHC results in a higher degree of healing when compared to surgical treatment of fistulas, which is a standard treatment. The volume of fistulas treated with mfNHC is decreased sixfold compared to the surgical treatment control. Molecular studies reveal that utilization of mfNHC reduced local inflammation and improved tissue regeneration. This study demonstrates that ADSC-loaded mfNHC is a promising therapy for CD-PAF, and warrants further studies to advance mfNHC toward clinical translation.

Commensal microbiome promotes hair follicle regeneration by inducing keratinocyte HIF-1α signaling and glutamine metabolism

Tissue injury induces metabolic changes in stem cells, which likely modulate regeneration. Using a model of organ regeneration called wound-induced hair follicle neogenesis (WIHN), we identified skin-resident bacteria as key modulators of keratinocyte metabolism, demonstrating a positive correlation between bacterial load, glutamine metabolism, and regeneration. Specifically, through comprehensive multiomic analysis and single-cell RNA sequencing in murine skin, we show that bacterially induced hypoxia drives increased glutamine metabolism in keratinocytes with attendant enhancement of skin and hair follicle regeneration. In human skin wounds, topical broad-spectrum antibiotics inhibit glutamine production and are partially responsible for reduced healing. These findings reveal a conserved and coherent physiologic context in which bacterially induced metabolic changes improve the tolerance of stem cells to damage and enhance regenerative capacity. This unexpected proregenerative modulation of metabolism by the skin microbiome in both mice and humans suggests important methods for enhancing regeneration after injury.

A 10-Year Review of Surgical Outcomes at the Johns Hopkins and University of Maryland Resident Aesthetic Clinic

Background

In 2014, the Plastic Surgery Residency Review Committee of the Accreditation Council for Graduate Medical Education (ACGME) increased minimum aesthetic surgery requirements. Consequently, the resident aesthetic clinic (RAC) has become an ever more important modality for training plastic surgery residents.

Objectives

To analyze demographics and long-term surgical outcomes of aesthetic procedures performed at the Johns Hopkins and University of Maryland (JH/UM) RAC. A secondary objective was to evaluate the JH/UM RAC outcomes against those of peer RACs as well as board-certified plastic surgeons.

Methods

We performed a retrospective chart review of all patients who underwent aesthetic procedures at the JH/UM RAC between 2011 and 2020. Clinical characteristics, minor complication rates, major complication rates, and revision rates from the JH/UM RAC were compared against 2 peer RACs. We compared the incidence of major complications between the JH/UM RAC and a cohort of patients from the CosmetAssure (Birmingham, AL) database. Pearson's chi-square test was used to compare complication rates between patient populations, with a significance set at 0.05.

Results

Four hundred ninety-five procedures were performed on 285 patients. The major complications rate was 1.0% (n = 5). Peer RACs had total major complication rates of 0.2% and 1.7% (P = .07 and P = .47, respectively). CosmetAssure patients matched to JH/UM RAC patients were found to have comparable total major complications rates of 1.8% vs 0.6% (P = .06), respectively. At JH/UM, the minor complication rate was 13.9%, while the revision rate was 5.9%.

Conclusions

The JH/UM RAC provides residents the education and training necessary to produce surgical outcomes comparable to peer RACs as well as board-certified plastic surgeons.

Level of Evidence 3

Biostimulatory Micro-Fragmented Nanofiber-Hydrogel Composite Improves Mesenchymal Stem Cell Delivery and Soft Tissue Remodeling

Functional microgels are preferred stem cell carriers due to the ease of delivery through minimally invasive injection and seamless integration with the surrounding host tissue. A biostimulatory nanofiber-hydrogel composite (NHC) has been previously developed through covalently crosslinking a hyaluronic acid hydrogel network with surface-functionalized poly (ε-caprolactone) nanofiber fragments. The NHC mimics the microarchitecture of native soft tissue matrix, showing enhanced cell infiltration, immunomodulation, and proangiogenic properties. Here, injectability of the pre-formed NHC is improved by mechanical fragmentation, making it into micro-fragmented NHC (mfNHC) in a granular gel form as a stem cell carrier to deliver mesenchymal stem cells (MSCs) for soft tissue remodeling. The mfNHC shows a similar storage modulus but a significantly reduced injection force, as compared with the corresponding bulk NHC. When injected subcutaneously in a rat model, mfNHC-MSC constructs initiate an elevated level of host macrophage infiltration, more pro-regenerative polarization, and subsequently, improved angiogenesis and adipogenesis response when compared to mfNHC alone. A similar trend of host cell infiltration and pro-angiogenic response is detected in a swine model with a larger volume injection. These results suggest a strong potential for use of the mfNHC as an injectable carrier for cell delivery and soft tissue remodeling.

Multi-step screening of DNA/lipid nanoparticles and co-delivery with siRNA to enhance and prolong gene expression

Lipid nanoparticles hold great potential as an effective non-viral vector for nucleic acid-based gene therapy. Plasmid DNA delivery can result in extended transgene expression compared to mRNA-based technologies, yet there is a lack of systematic investigation into lipid nanoparticle compositions for plasmid DNA delivery. Here, we report a multi-step screening platform to identify optimized plasmid DNA lipid nanoparticles for liver-targeted transgene expression. To achieve this, we analyze the role of different helper lipids and component ratios in plasmid DNA lipid nanoparticle-mediated gene delivery in vitro and in vivo. Compared to mRNA LNPs and in vivo-jetPEI/DNA nanoparticles, the identified plasmid DNA lipid nanoparticles successfully deliver transgenes and mediate prolonged expression in the liver following intravenous administration in mice. By addressing different physiological barriers in a stepwise manner, this screening platform can efficiently down select effective lipid nanoparticle candidates from a lipid nanoparticle library of over 1000 formulations. In addition, we substantially extend the duration of plasmid DNA nanoparticle-mediated transgene expression using a DNA/siRNA co-delivery approach that targets transcription factors regulating inflammatory response pathways. This lipid nanoparticle-based co-delivery strategy further highlights the unique advantages of an extended transgene expression profile using plasmid DNA delivery and offers new opportunities for DNA-based gene medicine applications.

Plasmid DNA offers extended transgene expression duration compared to mRNA technologies. Here, using a multi-step screening platform, the authors report the best performing nanoparticle formulations for liver-targeted plasmid DNA expression in vivo.

Mechanical tension mobilizes Lgr6+ epidermal stem cells to drive skin growth

Uniquely among mammalian organs, skin is capable of marked size change in adults, yet the mechanisms underlying this notable capacity are unclear. Here, we use a system of controlled tissue expansion in mice to uncover cellular and molecular determinants of skin growth. Through machine learning-guided three-dimensional tissue reconstruction, we capture morphometric changes in growing skin. We find that most growth is driven by the proliferation of the epidermis in response to mechanical tension, with more limited changes in dermal and subdermal compartments. Epidermal growth is achieved through preferential activation and differentiation of Lgr6⁺ stem cells of the epidermis, driven in part by the Hippo pathway. By single-cell RNA sequencing, we uncover further changes in mechanosensitive and metabolic pathways underlying growth control in the skin. These studies point to therapeutic strategies to enhance skin growth and establish a platform for understanding organ size dynamics in adult mammals.

Size-Controlled and Shelf-Stable DNA Particles for Production of Lentiviral Vectors

Polyelectrolyte complex particles assembled from plasmid DNA (pDNA) and poly(ethylenimine) (PEI) have been widely used to produce lentiviral vectors (LVVs) for gene therapy. The current batch-mode preparation for pDNA/PEI particles presents limited reproducibility in large-scale LVV manufacturing processes, leading to challenges in tightly controlling particle stability, transfection outcomes, and LVV production yield. Here we identified the size of pDNA/PEI particles as a key determinant for a high transfection efficiency with an optimal size of 400-500 nm, due to a cellular-uptake-related mechanism. We developed a kinetics-based approach to assemble size-controlled and shelf-stable particles using preassembled nanoparticles as building blocks and demonstrated production scalability on a scale of at least 100 mL. The preservation of colloidal stability and transfection efficiency was benchmarked against particles generated using an industry standard protocol. This particle manufacturing method effectively streamlines the viral manufacturing process and improves the production quality and consistency.

Neuroma of The Supraorbital Nerve Following Forehead Flap Reconstruction - Presentation and Surgical Management

ABSTRACT

Localized pain or headache from neuroma formation is a rare and challenging complication of forehead flap surgery. Here the authors present a patient who developed local pain and dysesthesia following iatrogenic injury to the left supraorbital nerve during forehead flap elevation. Following a diagnostic nerve block in clinic, surgical excision of the neuroma was performed through an upper blepharoplasty approach. The patient had immediate postoperative pain relief and remains pain free at fifteen-month follow-up. The authors describe etiology, workup, and surgical management of sensory nerve injury during forehead flap reconstruction.

Bacteria induce skin regeneration via IL-1β signaling

Environmental factors that enhance regeneration are largely unknown. The immune system and microbiome are attributed roles in repairing and regenerating structure but their precise interplay is unclear. Here, we assessed the function of skin bacteria in wound healing and wound-induced hair follicle neogenesis (WIHN), a rare adult organogenesis model. WIHN levels and stem cell markers correlate with bacterial counts, being lowest in germ-free (GF), intermediate in conventional specific pathogen-free (SPF), and highest in wild-type mice, even those infected with pathogenic Staphylococcus aureus. Reducing skin microbiota via cage changes or topical antibiotics decreased WIHN. Inflammatory cytokine IL-1β and keratinocyte-dependent IL-1R-MyD88 signaling are necessary and sufficient for bacteria to promote regeneration. Finally, in a small trial, a topical broad-spectrum antibiotic also slowed skin wound healing in adult volunteers. These results demonstrate a role for IL-1β to control morphogenesis and support the need to reconsider routine applications of topical prophylactic antibiotics.

Wound Induced Hair Neogenesis - A Novel Paradigm for Studying Regeneration and Aging

Hair follicles are the signature dermal appendage of mammals. They can be thought of as mini-organs with defined polarity, distinct constituent cell types, dedicated neurovascular supply, and specific stem cell compartments. Strikingly, some mammals show a capacity for adult hair follicle regeneration in a phenomenon known as wound-induced hair neogenesis (WIHN). In WIHN functional hair follicles reemerge during healing of large cutaneous wounds, and they can be counted to provide an index of regeneration. While age-related decline in hair follicle number and cycling are widely appreciated in normal physiology, it is less clear whether hair follicle regeneration also diminishes with age. WIHN provides an extraordinary quantitative system to address questions of mammalian regeneration and aging. Here we review cellular and molecular underpinnings of WIHN, explore known age-related changes to these elements, and present unanswered questions for future exploration.

Tissue Engineering of Axially Vascularized Soft-Tissue Flaps with a Poly-(ɛ-Caprolactone) Nanofiber-Hydrogel Composite

Objective: To develop a novel approach for tissue engineering of soft-tissue flaps suitable for free microsurgical transfer, using an injectable nanofiber hydrogel composite (NHC) vascularized by an arteriovenous (AV) loop. Approach: A rat AV loop model was used for tissue engineering of vascularized soft-tissue flaps. NHC or collagen-elastin (CE) scaffolds were implanted into isolation chambers together with an AV loop and explanted after 15 days. Saphenous veins were implanted into the scaffolds as controls. Neoangiogenesis, ultrastructure, and protein expression of SYNJ2BP, EPHA2, and FOXC1 were analyzed by immunohistochemistry and compared between the groups. Rheological properties were compared between the two scaffolds and native human adipose tissue. Results: A functional neovascularization was evident in NHC flaps with its amount being comparable with CE flaps. Scanning electron microscopy revealed a strong mononuclear cell infiltration along the nanofibers in NHC flaps and a trend toward higher fiber alignment compared with CE flaps. SYNJ2BP and EPHA2 expression in endothelial cells (ECs) was lower in NHC flaps compared with CE flaps, whereas FOXC1 expression was increased in NHC flaps. Compared with the stiffer CE flaps, the NHC flaps showed similar rheological properties to native human adipose tissue. Innovation: This is the first study to demonstrate the feasibility of tissue engineering of soft-tissue flaps with similar rheological properties as human fat, suitable for microsurgical transfer using an injectable nanofiber hydrogel composite. Conclusions: The injectable NHC scaffold is suitable for tissue engineering of axially vascularized soft-tissue flaps with a solid neovascularization, strong cellular infiltration, and biomechanical properties similar to human fat. Our data indicate that SYNJ2BP, EPHA2, and FOXC1 are involved in AV loop-associated angiogenesis and that the scaffold material has an impact on protein expression in ECs.

Nasolabial and forehead flap reconstruction of contiguous alar-upper lip defects

BACKGROUND

Defects of the nasal ala and upper lip aesthetic subunits can be challenging to reconstruct when they occur in isolation. When defects incorporate both the subunits, the challenge is compounded as subunit boundaries also require reconstruction, and local soft tissue reservoirs alone may provide inadequate coverage. In such cases, we used nasolabial flaps for upper lip reconstruction and a forehead flap for alar reconstruction.

METHODS

Three men and three women aged 21-79 years (average, 55 years) were treated for defects of the nasal ala and upper lip that resulted from cancer (n = 4) and trauma (n = 2). Unaffected contralateral subunits dictated the flap design. The upper lip subunit was excised and replaced with a nasolabial flap. The flap, depending on the contralateral reference, determined accurate alar base position. A forehead flap resurfaced or replaced the nasal ala. Autologous cartilage was used in every case to fortify the forehead flap reconstruction.

RESULTS

Patients were followed for 25.6 months (range, 1-4 years). All the flaps survived, and there were no complications. Satisfactory aesthetic results were achieved in every case. With the exception of a small vertical cheek scar and a vertical forehead scar, all incisions were concealed within the subunit borders.

CONCLUSION

From preliminary experience, we advocate combining nasolabial flap reconstruction of the upper lip with a forehead flap reconstruction of the ala to preserve normal facial appearance. This combination addresses an important void in the algorithmic approach to central facial reconstruction.

Double forehead flap reconstruction of composite nasal defects

BACKGROUND AND AIM

Composite nasal defects require skin, framework, and lining reconstruction. The forehead flap is an ideal donor for skin coverage because of good color match and excellent donor-site healing. Intranasal flaps and grafts are reserved for lining reconstruction of small defects. Locoregional and free flaps are used for larger lining defects, but these may not be ideal or safe. The authors advocate the double forehead flap for large composite defects of the nose in a subset of patients.

METHODS

Three men and three women aged 55-87 years (average 74.7 years) were treated for composite nasal defects that resulted from cancer (n = 5) and trauma (n = 1). Skin and lining defects were >2 cm in every dimension. Double forehead flaps were raised in stages (n = 1) or simultaneously (n = 5), and nasal reconstruction was performed in two (n = 1) or three stages (n = 5).

RESULTS

Patients were followed for 19.3 months (range 13-24 months). Donor sites of flaps raised in stages healed after 3 months. When flaps were raised together, healing required 5-13 months (average 7.6 months). There were no partial or complete flap losses. None of the patients had infection, hematoma, or nerve injury. Satisfactory aesthetic results were achieved in every case.

CONCLUSION

The authors advocate the double forehead flap for large composite nasal defects in patients who are not suitable candidates for nasolabial flaps and those who may not tolerate free tissue transfer. The advantages of this method must be weighed against the drawbacks, which include prolonged donor-site healing and elimination of the contralateral forehead flap.

dsRNA Released by Tissue Damage Activates TLR3 to Drive Skin Regeneration

Regeneration of skin and hair follicles after wounding--a process known as wound-induced hair neogenesis (WIHN)--is a rare example of adult organogenesis in mammals. As such, WIHN provides a unique model system for deciphering mechanisms underlying mammalian regeneration. Here, we show that dsRNA, which is released from damaged skin, activates Toll-Like Receptor 3 (TLR3) and its downstream effectors IL-6 and STAT3 to promote hair follicle regeneration. Conversely, TLR3-deficient animals fail to initiate WIHN. TLR3 activation promotes expression of hair follicle stem cell markers and induces elements of the core hair morphogenetic program, including ectodysplasin A receptor (EDAR) and the Wnt and Shh pathways. Our results therefore show that dsRNA and TLR3 link the earliest events of mammalian skin wounding to regeneration and suggest potential therapeutic approaches for promoting hair neogenesis.

The thinning top: why old people have less hair

Changes in the hair cycle underlie age-related alopecia, but the causative mechanisms have remained unclear. Chen et al. point to an imbalance between stem cell-activating and -inhibitory signals as the key determinant of age-related regenerative decline. Further, they identify a secreted protein, follistatin, that may be able to shift the balance toward renewal.

Laparoscopic major hepatectomy: pure laparoscopic approach versus hand-assisted technique

Laparoscopic liver resections are being performed with increasing frequency, with several groups having reported minimally invasive approaches for major anatomic hepatic resections. Some surgeons favor a pure laparoscopic approach, while others prefer a hand-assisted approach for major laparoscopic liver resections. There are clear advantages and disadvantages to a hand-assisted technique. The purpose of this study is to summarize the literature comparing pure laparoscopic and hand-assisted approaches for minimally invasive hepatic resection, and to describe our approach in 432 laparoscopic liver resections.

Le Fort II fractures are associated with death: a comparison of simple and complex midface fractures

PURPOSE

To investigate whether complex midface fractures have a greater association with death and intracranial injury than simple midface fractures.

MATERIALS AND METHODS

A retrospective chart review was performed for patients with blunt-mechanism midface fractures who had presented to an urban trauma center from 1998 to 2010. The survival and intracranial injury status was evaluated for patients with simple and complex midface fractures, including Le Fort, naso-orbitoethmoid, and/or zygomaticomaxillary fractures. Intracranial injury included hemorrhage and brainstem injury. Patients with upper face fractures were excluded to minimize confounding. Adjusted relative risk estimates were obtained using multivariate regression analysis.

RESULTS

Of 3,291 patients with midface fractures, 213 (6.3%) died and 693 (21.3%) had an intracranial injury. The cumulative mortality reached 11.6% in patients with complex midface fractures and 5.1% in those with simple midface fractures (P < .001). Patients with complex midface fractures were 57% more likely to die (relative risk = 1.57; P < .005). Specifically, Le Fort II fractures independently conferred a 94% increased risk of death (relative risk = 1.94; P < .01), but Le Fort I and III fractures were not significantly associated with death. Among patients presenting without neurologic impairment, those with Le Fort II and III fractures remained 2.88-fold (P < .01) and 2.54-fold (P < .001) more likely to have an underlying intracranial injury, respectively.

CONCLUSIONS

Le Fort II fractures are associated with increased mortality. Furthermore, Le Fort II and III fractures are associated with serious intracranial injury, even in the absence of alterations in consciousness. These patients should be monitored with heightened vigilance and followed up closely during hospitalization, regardless of the presenting clinical findings.

Orthodontic uprighting of impacted mandibular permanent second molar: a case report

The mandibular second molars can become impacted beneath the crown of the first molars due to various causes and fail to erupt normally. Presented herewith is a case report of orthodontic uprighting of a mesioangular impacted mandibular right permanent second molar. Though various treatment options were available, an uprighting push spring appliance was used as it is easy to fabricate and produces distal tipping and uprighting of the impacted tooth without the necessity of surgical assistance, bone removal, or splinting. The uprighting of the mandibular second molar was achieved within two months.

Ubiquitination by the anaphase-promoting complex drives spindle checkpoint inactivation

Eukaryotic cells rely on a surveillance mechanism known as the spindle checkpoint to ensure accurate chromosome segregation. The spindle checkpoint prevents sister chromatids from separating until all kinetochores achieve bipolar attachments to the mitotic spindle. Checkpoint proteins tightly inhibit the anaphase-promoting complex (APC), a ubiquitin ligase required for chromosome segregation and progression to anaphase. Unattached kinetochores promote the binding of checkpoint proteins Mad2 and BubR1 to the APC-activator Cdc20, rendering it unable to activate APC. Once all kinetochores are properly attached, however, cells inactivate the checkpoint within minutes, allowing for the rapid and synchronous segregation of chromosomes. How cells switch from strong APC inhibition before kinetochore attachment to rapid APC activation once attachment is complete remains a mystery. Here we show that checkpoint inactivation is an energy-consuming process involving APC-dependent multi-ubiquitination. Multi-ubiquitination by APC leads to the dissociation of Mad2 and BubR1 from Cdc20, a process that is reversed by a Cdc20-directed de-ubiquitinating enzyme. The mutual regulation between checkpoint proteins and APC leaves the cell poised for rapid checkpoint inactivation and ensures that chromosome segregation promptly follows the completion of kinetochore attachment. In addition, our results suggest a mechanistic basis for how cancer cells can have a compromised spindle checkpoint without corresponding mutations in checkpoint genes.

The contralateral slip

Between July 1994 and June 2004, 60 patients with 76 slipped upper femoral epiphyses were managed within the adult trauma service of three hospitals. Treatment was by a single cannulated screw.

Of these cases, 53 were unilateral, in 17 of which uncomplicated prophylactic fixation of the contralateral hip was performed. Of the other 36 cases, nine presented with a subsequent slip despite ongoing out-patient care. The subsequent slip was unpredictable in timing and unrelated to the age at the initial slip. It was more often unstable and in one case avascular necrosis developed. The overall rate of avascular necrosis, although in accordance with the literature, was 60% in acute unstable slips with a slip angle greater than 40°.

In our experience, prophylactic fixation was safer than continued observation of the contralateral hip.

The processivity of multiubiquitination by the APC determines the order of substrate degradation

The anaphase-promoting complex (APC) coordinates mitosis and G1 by sequentially promoting the degradation of key cell-cycle regulators. Following the degradation of its substrates in G1, the APC catalyzes the autoubiquitination of its E2 UbcH10. This stabilizes cyclin A and allows it to inactivate APC(Cdh1). How the APC establishes this complex temporal sequence of ubiquitinations, referred to as substrate ordering, is not understood. Here we show that substrate ordering depends on the relative processivity of substrate multiubiquitination by the APC. Processive substrates obtain ubiquitin chains in a single APC binding event. The multiubiquitination of distributive substrates requires multiple rounds of APC binding, which render it sensitive to lower APC concentrations, competition by processive substrates, and deubiquitination. Consequently, more processive substrates are preferentially multiubiquitinated in vitro and degraded earlier in vivo. The processivity of multiubiquitination is strongly influenced by the D box within the substrate, suggesting that substrate ordering is established by a mechanism intrinsic to APC and its substrates and similar to kinetic proofreading.

Chronic ethanol and nicotine interaction on rat tissue antioxidant defense system

Ethanol consumption and cigarette smoking are common in societies worldwide and have been identified as injurious to human health. This study was undertaken to examine the interactive effects of chronic ethanol and nicotine consumption on the antioxidant defense system in different tissues of rat. Male Fisher-344 rats were divided into four groups of five animals each and treated for 6.5 weeks as follows: (1) Control rats were administered normal saline orally; (2) ethanol (20% [wt./vol.]) was given orally at a dose of 2 g/kg; (3) nicotine was administered subcutaneously at a dose of 0.1 mg/kg; and (4) a combination of ethanol plus nicotine was administered by the route and at the dose described above. The animals were killed 20 h after the last treatment, and liver, lung, kidney, and testes were isolated and analyzed. Chronic ingestion of ethanol resulted in a significant depletion of glutathione (GSH) content in liver, lung, and testes, whereas chronic administration of nicotine significantly depleted GSH content in liver and testes. The combination of ethanol plus nicotine resulted in a significant depletion of GSH content in liver, lung, and testes. Ethanol, nicotine, or a combination of ethanol plus nicotine significantly increased superoxide dismutase (SOD) activity in liver and decreased SOD activity in kidney. Ethanol, nicotine, or a combination of ethanol plus nicotine significantly decreased catalase (CAT) activity in liver and increased CAT activity in kidney and testes. Chronic ingestion of ethanol resulted in a significant decrease in glutathione peroxidase (GSH-Px) activity in liver and kidney, whereas a combination of ethanol plus nicotine increased GSH-Px activity in liver and decreased GSH-Px activity in kidney and testes. Ethanol, nicotine, or a combination of ethanol plus nicotine significantly increased lipid peroxidation, respectively, in liver. It is suggested that prolonged exposure to ethanol and nicotine produce similar, and in some cases additive, oxidative tissue injuries in rat.

Eukaryotic-like adenylyl cyclases in Mycobacterium tuberculosis H37Rv: cloning and characterization

Screening the Mycobacterium tuberculosis H37Rv genomic library for complementation of catabolic defect for cAMP-dependent expression of maltose operon produced the adenylyl cyclase gene (Mtb cya, (1997)) annotated later as Rv1625c (Cole, S. T., Brosch, R., Parkhill, J., Garnier, T., Churcher, C., Harris, D., Gordon, S. V., Eiglmeier, K., Gas, S., Barry, C. E., III, et al. (1998) Nature 393, 537-544). The deduced amino acid (aa) sequence (443 aa) encoded by Mtb cya contains a single hydrophobic domain of six transmembrane helices (152 aa) in the amino-terminal half of the protein. Flanking this domain are an arginine-rich (17%) amino-terminal cytoplasmic tail (46 aa) and a carboxyl-terminal cytoplasmic domain (245 aa) with extensive homology to the catalytic core of eukaryotic adenylyl cyclases. Site-directed mutagenesis of Arg(43) and Arg(44) to alanine/glycine showed a loss of adenylyl cyclase activity, whereas mutagenesis to lysine restored the activity. Hence it is proposed that the formation of the catalytic site in Mtb adenylyl cyclase requires an interaction between Arg(43) and Arg(44) residues in the distal cytoplasmic tail and the carboxyl-terminal cytoplasmic domain. Mtb adenylyl cyclase activity at the physiological concentration of ATP (1 mm) was 475 nmol of cAMP/min/mg of membrane protein in the presence of Mn(2+) but only 10 nmol of cAMP/min/mg of membrane protein in the presence of Mg(2+). The physiological significance of the activation of Mtb adenylyl cyclase by Mn(2+) is discussed in view of the presence of manganese transporter protein in mycobacteria and macrophages wherein mycobacteria reside.

Autoantibodies to IA-2 and GAD65 in patients with type 2 diabetes mellitus of varied duration: prevalence and correlation with clinical features

OBJECTIVE

To determine the prevalence of autoantibodies to IA-2 (IA-2Ab) and glutamic acid decarboxylase (GADAb) in type 2 diabetes, their relationship to disease duration, and their importance in management decisions.

METHODS

We undertook a study of 101 patients with type 2 diabetes (defined as nonketotic hyperglycemia at diagnosis) of varied duration (median, 4 years). Results were compared with those from 36 patients with type 1 diabetes also of varied duration (median, 2 years). IA-2Ab and GADAb were measured by radioligand-binding assays with use of in vitro-synthesized, 35S-labeled antigens.

RESULTS

Of the 101 patients with type 2 diabetes, 20 (20%) were positive for GADAb; only 4 of these 20 were positive for IA-2Ab. In comparison, 75% of patients with type 1 diabetes were positive for GADAb, IA-2Ab, or both (P<0.0001). The coincidence of IA-2Ab positivity in GADAb-positive patients with type 2 diabetes was significantly lower than in patients with type 1 diabetes (20% versus 73%, respectively; P = 0.002). All four IA-2Ab- and GADAb-positive patients with type 2 diabetes required insulin and were younger than those positive for GADAb alone (P = 0.018). GADAb positivity in patients with type 2 diabetes was highly associated with insulin requirement (P = 0.004), with an odds ratio of 5.8 in predicting insulin dependence. Among patients with type 2 diabetes receiving insulin therapy, disease duration was significantly shorter (P = 0.025) and body mass index was significantly lower (P<0.001) in GADAb-positive versus GADAb-negative patients. In contrast to type 1 diabetes, in which GADAb values were negatively correlated with disease duration (r = -0.34; P = 0.044), no significant correlation with disease duration was observed in type 2 diabetes (r = -0.166; P = 0.48).

CONCLUSION

Irrespective of duration of disease, measurement of IA-2Ab and GADAb can help to identify those patients with type 2 diabetes most likely to require insulin therapy.

Breakthrough pain in cancer patients: new therapeutic approaches to an old challenge

Breakthrough pain is a well recognized but ill-defined phenomenon that occurs commonly in the presence of otherwise stable, persistent pain. It is defined now as a "transient pain episode that occurs, or breaks through from the otherwise stable background pain." Breakthrough pain is usually associated with moderate to severe pain and may form a predictor of poor response to treatment with routine pharmacotherapy. Breakthrough pain is also associated with functional impairment and psychological distress. The assessment and treatment should be multidimensional. Although primary therapies such as chemotherapy, radiation treatment, and surgical options are explored, the mainstay of treatment is pharmacotherapy. Nonpharmacologic methods, such as orthotic devices and joint stabilizations along with behavioral methods, should be explored. Anesthetic and neurosurgical procedures are performed on a limited number of patients based on the prognosis, intractable nature of pain, and favorable risk/benefit ratio. Newer oral transmucosal fentanyl offers a favorable pharmacokinetic and pharmacodynamic profile and ease of administration.

The utility of urgent colonoscopy in the evaluation of acute lower gastrointestinal tract bleeding: a 2-year experience from a single center

OBJECTIVE

Urgent colonoscopy is often recommended to evaluate acute rectal bleeding. However, it may not identify a source because of blood in the lumen or inadequate preparation. Our aim was to determine the utility of urgent colonoscopy as the initial test for acute rectal bleeding.

METHODS

This was a retrospective chart review of all patients discharged in 1997 and 1998 with an International Classification of Diseases, 9th Revision, code for hematochezia or rectal bleeding.

RESULTS

We identified 514 charts but excluded 424 because of inaccurate coding. In the 90 with confirmed acute rectal bleeding, colonoscopy was the initial test in 39; age, sex, and race distributions were similar to those who did not have colonoscopy. A definite source of bleeding was seen at colonoscopy in only three patients, a probable source in 26, and no source in 10. Therapeutic intervention in four patients with a definite or probable source was successful in three. The commonest reasons for not performing urgent colonoscopy were bleeding from presumed hemorrhoids or bleeding that was clinically insignificant. Spontaneous resolution of bleeding and length of hospital stay were not affected by urgent colonoscopy. Five patients had surgery for unrelated reasons. In-hospital mortality was 2% and was unrelated to bleeding.

CONCLUSION

Urgent colonoscopy as the initial investigation in acute lower GI tract bleeding probably does not alter the outcome in most cases. Identification of a definite bleeding source leading to successful therapeutic intervention is rare. Spontaneous resolution is frequent, length of hospital stay is similar, and clinical outcome is excellent regardless of whether or not urgent colonoscopy is performed.

Oxygen consumption and respiration following two yoga relaxation techniques

The present study was conducted to evaluate a statement in ancient yoga texts that suggests that a combination of both "calming" and "stimulating" measures may be especially helpful in reaching a state of mental equilibrium. Two yoga practices, one combining "calming and stimulating" measures (cyclic meditation) and the other, a "calming" technique (shavasan), were compared. The oxygen consumption, breath rate, and breath volume of 40 male volunteers (group mean +/- SD, 27.0 +/- 5.7 years) were assessed before and after sessions of cyclic meditation (CM) and before and after sessions of shavasan (SH). The 2 sessions (CM, SH) were 1 day apart. Cyclic meditation includes the practice of yoga postures interspersed with periods of supine relaxation. During SH the subject lies in a supine position throughout the practice. There was a significant decrease in the amount of oxygen consumed and in breath rate and an increase in breath volume after both types of sessions (2-factor ANOVA, paired t test). However, the magnitude of change on all 3 measures was greater after CM: (1) Oxygen consumption decreased 32.1% after CM compared with 10.1% after SH; (2) breath rate decreased 18.0% after CM and 15.2% after SH; and (3) breath volume increased 28.8% after CM and 15.9% after SH. These results support the idea that a combination of yoga postures interspersed with relaxation reduces arousal more than relaxation alone does.

Opioid and Nonopioid Therapy in Cancer Pain: The Traditional and the New

Management of cancer pain has made sidnificant progress in recent years, partly due to the Agency for Health Care Policy and Research (AHCPR) guidelines, but mostly it seems to be due to the death and dying movement in the world. However, cancer pain on occasion poses significant problems and needs accurate diganosis and appropriate intervention. Pharmacotherapy remains the mainstay of treating cancer pain. Most cancer pain syndromes present with moderate to severe pain, associated with several comorbid problems necessitating the multidisciplinary approach to optimally treat it. The psychologic factors associated wth serious illness, terminal prognoses, and dying complicate the scenario even more as compared with that of nonmalignant pain. Although such patients are entitled to more aggressive analgesic therapy, it is unfortunate that this is not achieved in a significant percentage of cases. In this review, we address some of the above issues and attempt to summarize the traditional pharmacologic therapies highlighting their modern modes of implementation in cancer pain management. Special emphasis on the state-of-the art innovations in this field wil be noted.

Neural blockade for abdominopelvic pain of oncologic origin

Neural blockade, like other accepted treatments for persistent pain, is not a panacea. Careful assessment is required to elicit the need for complementary interventions, including pharmacological management and psychobehavioral and rehabilitative approaches, combined with attention to the palliation of other symptoms. Celiac and superior hypogastric plexus blocks are well-accepted, effective, and minimally hazardous means for providing palliation of visceral abdominopelvic pain. Although they require radiological imaging, they are relatively undemanding of the experienced anesthesiologist pain specialist and do not deplete patients' limited resources and energy. Because of their uniquely favorable risk:benefit ratio, these procedures should be considered early in the course of treating patients with abdominopelvic pain that is expected to persist.

Effect of yoga training on maze learning

The performance in a maze learning task was assessed in adults of either sex (n = 31) before and after 30 days of yoga training and in an age and gender matched control group of subjects who did not receive training in yoga. Subjects were blind folded and used the dominant hand to trace the path in a wooden pencil maze. At each assessment, subjects were given 5 trials, without a gap between them. Performance was based on the time taken to complete the maze and the number of blind alleys taken. The time and error scores of Trial 1 were significantly less after yoga (two-factor ANOVA, Tukey test). Repeating trials significantly decreased time scores at Trial 5 versus Trial 1, for both groups on Day 1 and for the control group on Day 30. Hence the yoga group showed improved performance in maze tracing at retest 30 days later, which may be related to this group being faster learners and also the effect of yoga itself. Yoga training did not influence maze learning, based on the performance in 5 repeat trials.

Dose response of ethanol ingestion on antioxidant defense system in rat brain subcellular fractions

This study investigated the response of the antioxidant defense system in brain subcellular fractions after oral graded doses of ethanol to rat. Four groups of male Fischer-344 rats were orally administered saline, ethanol 2 g, 4 g, and 6 g/kg, respectively, and sacrificed 1 hour post treatment. Brain cytosol, synaptosomes, microsomes and mitochondria were separated by density gradient differential centrifugation and assayed for antioxidant system. A significant and dose-dependent-decrease in superoxide dismutase (SOD) activity was observed in all brain subcellular fractions. Catalase (CAT) activity was significantly decreased in brain mitochondria (67% and 80% of control) at higher doses of ethanol; whereas, CAT activity was significantly increased in cytosol, synaptosomes and microsomes. Glutathione peroxidase (GSH-Px) activity was significantly increased in all brain subcellular fractions except in cytosol at higher dose of ethanol. Malondialdehyde (MDA) content was significantly increased in all brain subcellular fractions showing dose response of ethanol-induced oxidative stress. The increase in MDA levels in the brain synaptosomes and microsomes were higher at 6 g dose of ethanol (155% and 163% of control) when compared to mitochondria and cytosol. Glutathione (GSH) levels were significantly increased in brain cytosol and microsomes at higher dose of ethanol (164% and 159% of control); whereas, the GSH concentration was significantly decreased in brain synaptosomes and mitochondria. The antioxidant enzyme (AOE) activity ratios (GSH-Px/SOD and GSH-Px + CAT/SOD) were dose dependently increased in all brain subcellular fractions, particularly in synaptosomes. The GSH/GSSG ratio was dose dependently increased in brain microsomes. The perturbations in the antioxidant defense system and enhanced lipid peroxidation following graded doses of ethanol ingestion indicate a dose-dependent-oxidative 2133stress response in brain subcellular compartments of rats.

Pain and loss of function in head and neck cancer survivors

Head and neck cancers are relatively uncommon malignancies and the characteristics of pain and functional impairments in survivors are not well studied. To characterize the incidence, location, severity, types and causes of pain; associated functional impairments, and pain management methods, the medical charts of 40 consecutive outpatients with biopsy-proven head and neck cancers were reviewed. Pain was severe in 52% (N = 21), and was located near sites of tumor origin. Pain was caused by tumor recurrence in 35% (N = 14), treatment sequelae in 30% (N = 12), multiple etiologies in 25% (N = 10), and unrelated causes in 10% (N = 4). Pains were mixed nociceptive and neuropathic pain in 37.5% (N = 15), nociceptive pain in 32.5% (N = 13), myofascial in 13.0% (N = 6), neuropathic in 7.5% (N = 3); and other mixed types in 7.5% (N = 3). Despite the high prevalence of dysphagia (82%), 60% used orally administered opioid-nonopioid analgesics. Physical disfigurement (87.5%; N = 35), dysphagia (62.5%, N = 25), and jaw dysfunction (40.0%; N = 16) were the most frequent physical impairments. Multiple regression analysis showed that the presence of skull base or mandibular bone involvement had significant influence on the severity of pain (P = 0.03, adjusted R2 0.25) We conclude that pain in head and neck cancer can be chronic, severe, and persistent despite completion of oncologic treatment.

Identification of profilin and src homology 3 domains as binding partners for Drosophila enabled

Drosophila Enabled (Ena) was first identified as a genetic suppressor of mutations in the Abelson tyrosine kinase and subsequently was shown to be a member of the Ena/vasodilator-stimulated phosphoprotein family of proteins. All members of this family have a conserved domain organization, bind the focal adhesion protein zyxin, and localize to focal adhesions and stress fibers. Members of this family are thought to be involved in the regulation of cytoskeleton dynamics. The Ena protein sequence has multiple poly-(L-proline) residues with similarity to both profilin and src homology 3 binding sites. Here, we show that Ena can bind directly to the Drosophila homolog of profilin, chickadee. Furthermore, Ena and profilin were colocalized in spreading cultured cells. We report that the proline-rich region of Ena is responsible for this interaction as well as for mediating binding to the src homology 3 domain of the Abelson tyrosine kinase. These data support the hypothesis that Ena provides a regulated link between signal transduction and cytoskeleton assembly in the developing Drosophila embryo.

Mutations in Drosophila enabled and rescue by human vasodilator-stimulated phosphoprotein (VASP) indicate important functional roles for Ena/VASP homology domain 1 (EVH1) and EVH2 domains

Drosophila Enabled (Ena) was initially identified as a dominant genetic suppressor of mutations in the Abelson tyrosine kinase and, more recently, as a member of the Ena/human vasodilator-stimulated phosphoprotein (VASP) family of proteins. We have used genetic, biochemical, and cell biological approaches to demonstrate the functional relationship between Ena and human VASP. In addition, we have defined the roles of Ena domains identified as essential for its activity in vivo. We have demonstrated that VASP rescues the embryonic lethality associated with loss of Ena function in Drosophila and have shown that Ena, like VASP, is associated with actin filaments and focal adhesions when expressed in cultured cells. To define sequences that are central to Ena function, we have characterized the molecular lesions present in two lethal ena mutant alleles that affected the Ena/VASP homology domain 1 (EVH1) and EVH2. A missense mutation that resulted in an amino acid substitution in the EVH1 domain eliminated in vitro binding of Ena to the cytoskeletal protein zyxin, a previously reported binding partner of VASP. A nonsense mutation that resulted in a C-terminally truncated Ena protein lacking the EVH2 domain failed to form multimeric complexes and exhibited reduced binding to zyxin and the Abelson Src homology 3 domain. Our analysis demonstrates that Ena and VASP are functionally homologous and defines the conserved EVH1 and EVH2 domains as central to the physiological activity of Ena.

Antigen-specific lymphoproliferative responses to tetanus toxoid: a means for the evaluation of Marek's disease virus-induced immunosuppression in chickens

Antigen-specific lymphoproliferative responses were examined in chickens following immunization with tetanus toxoid (Ttx). The immune competence of chickens was assessed by mitogen assay utilizing phytohemagglutinin (PHA)-stimulation and Ttx-specific antigen proliferation assay (Ttx-APA). Immune spleen cells but not peripheral blood leucocytes demonstrated specific proliferation following stimulation in vitro in a Ttx-APA. In this study, we examined firstly the effects of Marek's disease (MD)-associated immunosuppression on specific immune responses. The humoral and cell-mediated immune responses were monitored by enzyme-linked immunosorbent assay (ELISA) and Ttx-APA, respectively. Secondly, we examined if vaccination against MD using a conventional herpesvirus of turkeys (HVT) vaccine and two recombinant HVT (rHVT) vaccines would affect the development of Ttx-specific immune responses. The rHVT vaccines used in this study included two constructs: one expressing both Newcastle disease virus (NDV) and MD virus (MDV) genes (HVT/NDV/MDV), and another expressing only MDV genes (HVT/MDV). The mitogenic responses of spleen cells of the vaccinated chickens were inconsistent allowing no definitive conclusions about vaccinal immunosuppression. The results of the Ttx-APA indicated that Ttx-specific lymphoproliferative responses provide a meaningful measure of immunosuppression. The MDV-induced immunosuppression resulted in the inhibition of Ttx-specific lymphoproliferation in vitro. Both HVT and rHVT vaccines were not immunosuppressive as indicated by the development of normal Ttx-specific lymphoproliferative responses in chickens. These results indicate that vaccination against MD results not only in the prevention of tumor formation but also protection from possible virus-induced immunosuppression.