Stress-induced mucin 13 reductions drive intestinal microbiome shifts and despair behaviors

Depression is a prevalent psychological condition with limited treatment options. While its etiology is multifactorial, both chronic stress and changes in microbiome composition are associated with disease pathology. Stress is known to induce microbiome dysbiosis, defined here as a change in microbial composition associated with a pathological condition. This state of dysbiosis is known to feedback on depressive symptoms. While studies have demonstrated that targeted restoration of the microbiome can alleviate depressive-like symptoms in mice, translating these findings to human patients has proven challenging due to the complexity of the human microbiome. As such, there is an urgent need to identify factors upstream of microbial dysbiosis. Here we investigate the role of mucin 13 as an upstream mediator of microbiome composition changes in the context of stress. Using a model of chronic stress, we show that the glycocalyx protein, mucin 13, is selectively reduced after psychological stress exposure. We further demonstrate that the reduction of Muc13 is mediated by the Hnf4 transcription factor family. Finally, we determine that deleting Muc13 is sufficient to drive microbiome shifts and despair behaviors. These findings shed light on the mechanisms behind stress-induced microbial changes and reveal a novel regulator of mucin 13 expression.

Differential regulation of hair cell actin cytoskeleton mediated by SRF and MRTFB

The MRTF-SRF pathway has been extensively studied for its crucial role in driving the expression of a large number of genes involved in actin cytoskeleton of various cell types. However, the specific contribution of MRTF-SRF in hair cells remains unknown. In this study, we showed that hair cell-specific deletion of Srf or Mrtfb, but not Mrtfa, leads to similar defects in the development of stereocilia dimensions and the maintenance of cuticular plate integrity. We used fluorescence-activated cell sorting-based hair cell RNA-Seq analysis to investigate the mechanistic underpinnings of the changes observed in Srf and Mrtfb mutants, respectively. Interestingly, the transcriptome analysis revealed distinct profiles of genes regulated by Srf and Mrtfb, suggesting different transcriptional regulation mechanisms of actin cytoskeleton activities mediated by Srf and Mrtfb. Exogenous delivery of calponin 2 using Adeno-associated virus transduction in Srf mutants partially rescued the impairments of stereocilia dimensions and the F-actin intensity of cuticular plate, suggesting the involvement of Cnn2, as an Srf downstream target, in regulating the hair bundle morphology and cuticular plate actin cytoskeleton organization. Our study uncovers, for the first time, the unexpected differential transcriptional regulation of actin cytoskeleton mediated by Srf and Mrtfb in hair cells, and also demonstrates the critical role of SRF-CNN2 in modulating actin dynamics of the stereocilia and cuticular plate, providing new insights into the molecular mechanism underlying hair cell development and maintenance.

Repair of noise-induced damage to stereocilia F-actin cores is facilitated by XIRP2 and its novel mechanosensor domain

Prolonged exposure to loud noise has been shown to affect inner ear sensory hair cells in a variety of deleterious manners, including damaging the stereocilia core. The damaged sites can be visualized as 'gaps' in phalloidin staining of F-actin, and the enrichment of monomeric actin at these sites, along with an actin nucleator and crosslinker, suggests that localized remodeling occurs to repair the broken filaments. Herein, we show that gaps in mouse auditory hair cells are largely repaired within 1 week of traumatic noise exposure through the incorporation of newly synthesized actin. We provide evidence that Xin actin binding repeat containing 2 (XIRP2) is required for the repair process and facilitates the enrichment of monomeric γ-actin at gaps. Recruitment of XIRP2 to stereocilia gaps and stress fiber strain sites in fibroblasts is force-dependent, mediated by a novel mechanosensor domain located in the C-terminus of XIRP2. Our study describes a novel process by which hair cells can recover from sublethal hair bundle damage and which may contribute to recovery from temporary hearing threshold shifts and the prevention of age-related hearing loss.

Stress-induced despair behavior develops independently of the Ahr-RORγt axis in CD4 + cells

Current treatments for major depressive disorder are limited to neuropharmacological approaches and are ineffective for large numbers of patients. Recently, alternative means have been explored to understand the etiology of depression. Specifically, changes in the microbiome and immune system have been observed in both clinical settings and in mouse models. As such, microbial supplements and probiotics have become a target for potential therapeutics. A current hypothesis for the mechanism of action of these supplements is via the aryl hydrocarbon receptor's (Ahr) modulation of the T helper 17 cell (Th17) and T regulatory cell axis. As inflammatory RORγt + CD4 + Th17 T cells and their primary cytokine IL-17 have been implicated in the development of stress-induced depression, the connection between stress, the Ahr, Th17s and depression remains critical to understanding mood disorders. Here, we utilize genetic knockouts to examine the role of the microbial sensor Ahr in the development of stressinduced despair behavior. We observe an Ahr-independent increase in gut-associated Th17s in stressed mice, indicating that the Ahr is not responsible for this communication. Further, we utilized a CD4-specific RAR Related Orphan Receptor C (Rorc) knockout line to disrupt the production of Th17s. Mice lacking Rorc-produced IL-17 did not show any differences in behavior before or after stress when compared to controls. Finally, we utilize an unsupervised machine learning system to examine minute differences in behavior that could not be observed by traditional behavioral assays. Our data demonstrate that neither CD4 specific Ahr nor Rorc are necessary for the development of stress-induced anxiety- or depressive-like behaviors. These data suggest that research approaches should focus on other sources or sites of IL-17 production in stress-induced depression.

Cryptosporidium rhoptry effector protein ROP1 injected during invasion targets the host cytoskeletal modulator LMO7

The parasite Cryptosporidium invades and replicates in intestinal epithelial cells and is a leading cause of diarrheal disease and early childhood mortality. The molecular mechanisms that underlie infection and pathogenesis are largely unknown. Here, we delineate the events of host cell invasion and uncover a mechanism unique to Cryptosporidium. We developed a screen to identify parasite effectors, finding the injection of multiple parasite proteins into the host from the rhoptry organelle. These factors are targeted to diverse locations within the host cell and its interface with the parasite. One identified effector, rhoptry protein 1 (ROP1), accumulates in the terminal web of enterocytes through direct interaction with the host protein LIM domain only 7 (LMO7) an organizer of epithelial cell polarity and cell-cell adhesion. Genetic ablation of LMO7 or ROP1 in mice or parasites, respectively, impacts parasite burden in vivo in opposite ways. Taken together, these data provide molecular insight into how Cryptosporidium manipulates its intestinal host niche.

Adrenergic Mechanisms of Audiogenic Seizure-Induced Death in a Mouse Model of SCN8A Encephalopathy

Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death amongst patients whose seizures are not adequately controlled by current therapies. Patients with SCN8A encephalopathy have an elevated risk for SUDEP. While transgenic mouse models have provided insight into the molecular mechanisms of SCN8A encephalopathy etiology, our understanding of seizure-induced death has been hampered by the inability to reliably trigger both seizures and seizure-induced death in these mice. Here, we demonstrate that mice harboring an Scn8a allele with the patient-derived mutation N1768D (D/+) are susceptible to audiogenic seizures and seizure-induced death. In adult D/+ mice, audiogenic seizures are non-fatal and have nearly identical behavioral, electrographical, and cardiorespiratory characteristics as spontaneous seizures. In contrast, at postnatal days 20–21, D/+ mice exhibit the same seizure behavior, but have a significantly higher incidence of seizure-induced death following an audiogenic seizure. Seizure-induced death was prevented by either stimulating breathing via mechanical ventilation or by acute activation of adrenergic receptors. Conversely, in adult D/+ mice inhibition of adrenergic receptors converted normally non-fatal audiogenic seizures into fatal seizures. Taken together, our studies show that in our novel audiogenic seizure-induced death model adrenergic receptor activation is necessary and sufficient for recovery of breathing and prevention of seizure-induced death.

Myosin-VIIa is expressed in multiple isoforms and essential for tensioning the hair cell mechanotransduction complex

Mutations in myosin-VIIa (MYO7A) cause Usher syndrome type 1, characterized by combined deafness and blindness. MYO7A is proposed to function as a motor that tensions the hair cell mechanotransduction (MET) complex, but conclusive evidence is lacking. Here we report that multiple MYO7A isoforms are expressed in the mouse cochlea. In mice with a specific deletion of the canonical isoform (Myo7a-ΔC mouse), MYO7A is severely diminished in inner hair cells (IHCs), while expression in outer hair cells is affected tonotopically. IHCs of Myo7a-ΔC mice undergo normal development, but exhibit reduced resting open probability and slowed onset of MET currents, consistent with MYO7A's proposed role in tensioning the tip link. Mature IHCs of Myo7a-ΔC mice degenerate over time, giving rise to progressive hearing loss. Taken together, our study reveals an unexpected isoform diversity of MYO7A expression in the cochlea and highlights MYO7A's essential role in tensioning the hair cell MET complex.

Mechanisms of Hair Cell Damage and Repair

Sensory hair cells of the inner ear are exposed to continuous mechanical stress, causing damage over time. The maintenance of hair cells is further challenged by damage from a variety of other ototoxic factors, including loud noise, aging, genetic defects, and ototoxic drugs. This damage can manifest in many forms, from dysfunction of the hair cell mechanotransduction complex to loss of specialized ribbon synapses, and may even result in hair cell death. Given that mammalian hair cells do not regenerate, the repair of hair cell damage is important for continued auditory function throughout life. Here, we discuss how several key hair cell structures can be damaged, and what is known about how they are repaired.

LMO7 deficiency reveals the significance of the cuticular plate for hearing function

Sensory hair cells, the mechanoreceptors of the auditory and vestibular systems, harbor two specialized elaborations of the apical surface, the hair bundle and the cuticular plate. In contrast to the extensively studied mechanosensory hair bundle, the cuticular plate is not as well understood. It is believed to provide a rigid foundation for stereocilia motion, but specifics about its function, especially the significance of its integrity for long-term maintenance of hair cell mechanotransduction, are not known. We discovered that a hair cell protein called LIM only protein 7 (LMO7) is specifically localized in the cuticular plate and the cell junction. Lmo7 KO mice suffer multiple cuticular plate deficiencies, including reduced filamentous actin density and abnormal stereociliar rootlets. In addition to the cuticular plate defects, older Lmo7 KO mice develop abnormalities in inner hair cell stereocilia. Together, these defects affect cochlear tuning and sensitivity and give rise to late-onset progressive hearing loss.

Protein Synthesis Inhibition and Activation of the c-Jun N-Terminal Kinase Are Potential Contributors to Cisplatin Ototoxicity

Cisplatin has been regarded as an effective and versatile chemotherapeutic agent for nearly 40 years. Though the associated dose-dependent ototoxicity is known, the cellular mechanisms by which cochleovestibular hair cell death occur are not well understood. We have previously shown that aminoglycoside ototoxicity is mediated in part by cytosolic protein synthesis inhibition. Despite a lack of molecular similarity, aminoglycosides were shown to elicit similar stress pathways to cisplatin. We therefore reasoned that there may be some role of protein synthesis inhibition in cisplatin ototoxicity. Employing a modification of the bioorthogonal noncanonical amino acid tagging (BONCAT) method, we evaluated the effects of cisplatin on cellular protein synthesis. We show that cisplatin inhibits cellular protein synthesis in organ of Corti explant cultures. Similar to what was found after gentamicin exposure, cisplatin activates both the c-Jun N-terminal kinase (JNK) and mammalian target of rapamycin (mTOR) pathways. In contrast to aminoglycosides, cisplatin also inhibits protein synthesis in all cochlear cell types. We further demonstrate that the multikinase inhibitor sorafenib completely prevents JNK activation, while providing only moderate hair cell protection. Simultaneous stimulation of cellular protein synthesis by insulin, however, significantly improved hair cell survival in culture. The presented data provides evidence for a potential role of protein synthesis inhibition in cisplatin-mediated ototoxicity.

Accurate label-free protein quantitation with high- and low-resolution mass spectrometers

Label-free quantitation of proteins analyzed by tandem mass spectrometry uses either integrated peak intensity from the parent-ion mass analysis (MS1) or features from fragment-ion analysis (MS2), such as spectral counts or summed fragment-ion intensity. We directly compared MS1 and MS2 quantitation by analyzing human protein standards diluted into Escherichia coli extracts on an Orbitrap mass spectrometer. We found that summed MS2 intensities were nearly as accurate as integrated MS1 intensities, and both outperformed MS2 spectral counting in accuracy and linearity. We compared these results to those obtained from two low-resolution ion-trap mass spectrometers; summed MS2 intensities from LTQ and LTQ Velos instruments were similar in accuracy to those from the Orbitrap. Data from all three instruments are available via ProteomeXchange with identifier PXD000602. Abundance measurements using MS1 or MS2 intensities had limitations, however. While measured protein concentration was on average well-correlated with the known concentration, there was considerable protein-to-protein variation. Moreover, not all human proteins diluted to a mole fraction of 10(-3) or lower were detected, with a strong falloff below 10(-4) mole fraction. These results show that MS1 and MS2 intensities are simple measures of protein abundance that are on average accurate but should be limited to quantitation of proteins of intermediate to higher fractional abundance.

Correlation of actin crosslinker and capper expression levels with stereocilia growth phases

During development of the chick cochlea, actin crosslinkers and barbed-end cappers presumably influence growth and remodeling of the actin paracrystal of hair cell stereocilia. We used mass spectrometry to identify and quantify major actin-associated proteins of the cochlear sensory epithelium from E14 to E21, when stereocilia widen and lengthen. Tight actin crosslinkers (i.e. fascins, plastins, and espin) are expressed dynamically during cochlear epithelium development between E7 and E21, with FSCN2 replacing FSCN1 and plastins remaining low in abundance. Capping protein, a barbed-end actin capper, is located at stereocilia tips; it is abundant during growth phase II, when stereocilia have ceased elongating and are increasing in diameter. Capping protein levels then decline during growth phase III, when stereocilia reinitiate barbed-end elongation. Although actin crosslinkers are readily detected by electron microscopy in developing chick cochlea stereocilia, quantitative mass spectrometry of stereocilia isolated from E21 chick cochlea indicated that tight crosslinkers are present there in stoichiometric ratios relative to actin that are much lower than their ratios for vestibular stereocilia. These results demonstrate the value of quantitation of global protein expression in chick cochlea during stereocilia development.

Molecular architecture of the chick vestibular hair bundle

Hair bundles of the inner ear have a specialized structure and protein composition that underlies their sensitivity to mechanical stimulation. Using mass spectrometry, we identified and quantified >1,100 proteins, present from a few to 400,000 copies per stereocilium, from purified chick bundles; 336 of these were significantly enriched in bundles. Bundle proteins that we detected have been shown to regulate cytoskeleton structure and dynamics, energy metabolism, phospholipid synthesis and cell signaling. Three-dimensional imaging using electron tomography allowed us to count the number of actin-actin cross-linkers and actin-membrane connectors; these values compared well to those obtained from mass spectrometry. Network analysis revealed several hub proteins, including RDX (radixin) and SLC9A3R2 (NHERF2), which interact with many bundle proteins and may perform functions essential for bundle structure and function. The quantitative mass spectrometry of bundle proteins reported here establishes a framework for future characterization of dynamic processes that shape bundle structure and function.

Twist-off purification of hair bundles

Purification of hair bundles from inner-ear organs allows biochemical analysis of bundle constituents, including proteins and lipids. We describe here the "twist-off" method of bundle isolation, where dissected inner-ear organs are embedded in agarose, then subjected to a mechanical disruption that shears off bundles and leaves them in agarose blocks. With care in the dissection and in clean-up of the isolated bundles, contamination from cell bodies can be kept to a minimum. Isolated bundles can be analyzed by a variety of techniques, including immunocytochemistry, SDS-PAGE, immunoblotting, and mass spectrometry.

Hair bundles are specialized for ATP delivery via creatine kinase

When stimulated strongly, a hair cell's mechanically sensitive hair bundle may consume ATP too rapidly for replenishment by diffusion. To provide a broad view of the bundle's protein complement, including those proteins participating in energy metabolism, we used shotgun mass spectrometry methods to identify proteins of purified chicken vestibular bundles. In addition to cytoskeletal proteins, proteins involved in Ca(2+) regulation, and stress-response proteins, many of the most abundant bundle proteins that were identified by mass spectrometry were involved in ATP synthesis. After beta-actin, the cytosolic brain isoform of creatine kinase was the next most abundant bundle protein; at approximately 0.5 mM, creatine kinase is capable of maintaining high ATP levels despite 1 mM/s ATP consumption by the plasma-membrane Ca(2+)-ATPase. Consistent with this critical role in hair bundle function, the creatine kinase circuit is essential for high-sensitivity hearing as demonstrated by hearing loss in creatine kinase knockout mice.

The chloride intracellular channel protein CLIC5 is expressed at high levels in hair cell stereocilia and is essential for normal inner ear function

Although CLIC5 is a member of the chloride intracellular channel protein family, its association with actin-based cytoskeletal structures suggests that it may play an important role in their assembly or maintenance. Mice homozygous for a new spontaneous recessive mutation of the Clic5 gene, named jitterbug (jbg), exhibit impaired hearing and vestibular dysfunction. The jbg mutation is a 97 bp intragenic deletion that causes skipping of exon 5, which creates a translational frame shift and premature stop codon. Western blot and immunohistochemistry results confirmed the predicted absence of CLIC5 protein in tissues of jbg/jbg mutant mice. Histological analysis of mutant inner ears revealed dysmorphic stereocilia and progressive hair cell degeneration. In wild-type mice, CLIC5-specific immunofluorescence was detected in stereocilia of both cochlear and vestibular hair cells and also along the apical surface of Kolliker's organ during cochlear development. Refined immunolocalization in rat and chicken vestibular hair cells showed that CLIC5 is limited to the basal region of the hair bundle, similar to the known location of radixin. Radixin immunostaining appeared reduced in hair bundles of jbg mutant mice. By mass spectrometry and immunoblotting, CLIC5 was shown to be expressed at high levels in stereocilia of the chicken utricle, in an approximate 1:1 molar ratio with radixin. These results suggest that CLIC5 associates with radixin in hair cell stereocilia and may help form or stabilize connections between the plasma membrane and the filamentous actin core.

Physical and functional interaction between protocadherin 15 and myosin VIIa in mechanosensory hair cells

Hair cells of the mammalian inner ear are the mechanoreceptors that convert sound-induced vibrations into electrical signals. The molecular mechanisms that regulate the development and function of the mechanically sensitive organelle of hair cells, the hair bundle, are poorly defined. We link here two gene products that have been associated with deafness and hair bundle defects, protocadherin 15 (PCDH15) and myosin VIIa (MYO7A), into a common pathway. We show that PCDH15 binds to MYO7A and that both proteins are expressed in an overlapping pattern in hair bundles. PCDH15 localization is perturbed in MYO7A-deficient mice, whereas MYO7A localization is perturbed in PCDH15-deficient mice. Like MYO7A, PCDH15 is critical for the development of hair bundles in cochlear and vestibular hair cells, controlling hair bundle morphogenesis and polarity. Cochlear and vestibular hair cells from PCDH15-deficient mice also show defects in mechanotransduction. Together, our findings suggest that PCDH15 and MYO7A cooperate to regulate the development and function of the mechanically sensitive hair bundle.

Xenopus TRPN1 (NOMPC) localizes to microtubule-based cilia in epithelial cells, including inner-ear hair cells

In vertebrates, the senses of hearing and balance depend on hair cells, which transduce sounds with their hair bundles, containing actin-based stereocilia and microtubule-based kinocilia. A longstanding question in auditory science is the identity of the mechanically sensitive transduction channel of hair cells, thought to be localized at the tips of their stereocilia. Experiments in zebrafish implicated the transient receptor potential (TRP) channel NOMPC (drTRPN1) in this role; TRPN1 is absent from the genomes of higher vertebrates, however, and has not been localized in hair cells. Another candidate for the transduction channel, TRPA1, apparently is required for transduction in mammalian and nonmammalian vertebrates. This discrepancy raises the question of the relative contribution of TRPN1 and TRPA1 to transduction in nonmammalian vertebrates. To address this question, we cloned the TRPN1 ortholog from the amphibian Xenopus laevis, generated an antibody against the protein, and determined the protein's cellular and subcellular localization. We found that TRPN1 is prominently located in lateral-line hair cells, auditory hair cells, and ciliated epidermal cells of developing Xenopus embryos. In ciliated epidermal cells TRPN1 staining was enriched at the tips and bases of the cilia. In saccular hair cells, TRPN1 was located prominently in the kinocilial bulb, a component of the mechanosensory hair bundles. Moreover, we observed redistribution of TRPN1 upon treatment of hair cells with calcium chelators, which disrupts the transduction apparatus. This result suggests that although TRPN1 is unlikely to be the transduction channel of stereocilia, it plays an essential role, functionally related to transduction, in the kinocilium.

A T-type calcium channel required for normal function of a mammalian mechanoreceptor

The dorsal root ganglia (DRG) contain a variety of mechanoreceptors, but no molecular markers uniquely identify specific mechanoreceptor subtypes. We have used DNA microarrays and subtracted cDNA libraries to isolate genes that are specifically expressed by one type of mouse mechanoreceptor. The T-type calcium channel Ca(v)3.2 was exclusively expressed in the DRG by D-hair receptors, a very sensitive mechanoreceptor. Pharmacological blockade of T-type calcium channels indicated that this channel may be essential for normal D-hair receptor excitability including mechanosensitivity. This is the first evidence that a calcium channel is required for normal function of a vertebrate mechanoreceptor.

Neurotrophin-4: a survival factor for adult sensory neurons

The nerve growth factor (NGF) family of neurotrophins provides a substantial part of the normal trophic support for sensory neurons during development. Although these neurotrophins, which include Brain-Derived Neurotrophic Factor (BDNF), Neurotrophin-3 (NT-3), and Neurotrophin-4 (NT-4), continue to be expressed into adulthood, there is little evidence that they are survival factors for adult neurons. Here we have examined the age-dependent neurotrophic requirements of a specialized type of mechanoreceptive neuron, called a D-hair receptor, in the dorsal root ganglion (DRG). Studies using knockout mice have demonstrated that the survival of D-hair receptors is dependent upon both NT-3 and NT-4. Here, we show that the time period when D-hair receptors require these two neurotrophins is different. Survival of D-hair receptors depends on NT-3 early in postnatal development and NT-4 later in the mature animal. The age-dependent loss of D-hair neurons in older NT-4 knockout mice was accompanied by a large reduction (78%) in neurons positive for the NT-4 receptor (trkB) together with neuronal apoptosis in the DRG. This is the first evidence that sensory neurons have a physiological requirement for a single neurotrophin for their continued survival in the adult.

The usefulness of minimal F-wave latency and sural/radial amplitude ratio in diabetic polyneuropathy

The possibility of whether minimal F-wave latency and a simple ratio between the sural and superficial radial sensory response amplitudes may provide a useful electrodiagnostic test in diabetic patients was investigated in this report. To evaluate the diagnostic sensitivity of minimal F-wave latency, the Z-scores of the minimal F-wave latency, motor nerve conduction velocity (MCV), amplitude of compound muscle action potentials (CMAP), and distal latency (DL) of the median, ulnar, tibial, and peroneal nerve were compared in 37 diabetic patients. For the median, ulnar, and tibial nerves, the Z scores of the minimal F-wave latency were significantly larger than those of the MCV. In addition for all four motor nerves, the Z scores of the minimal F-wave latency were significantly larger than those for the CMAP amplitude. Furthermore, 19 subjects showing abnormal results in the standard sensory nerve conduction study had a significantly lower sural/radial amplitude ratio (SRAR), and 84% of them had an SRAR of less than 0.5. In conclusion, minimal F-wave latency and the ratio between the amplitudes of the sural and superficial radial sensory nerve action potential are sensitive measures for the detection of nerve pathology and should be considered in electrophysiologic studies of diabetic polyneuropathy.

Foot screening technique in a diabetic population

Foot complications are a well known factor which contribute to the morbidity of diabetes and increases the chance of amputation. A total of 126 consecutive diabetic patients were evaluated by diabetic foot screening. Forty-one patients showed an impaired protective sense when tested with Semmes-Weinstein monofilament 5.07 (10 g), and 92% of them showed peripheral polyneuropathy in nerve conduction study (NCS). The mean vibration score of the Rydel-Seiffer graduated tuning fork in patients with peripheral polyneuropathy in nerve conduction (NCV) study was 5.38+/-2.0, which was significantly different from that of patients without polyneuropathy in NCS. Among the deformities identified on examination, callus, corn, and hallux valgus were the greatest. While checking the ankle/ brachial index (ABI), we also evaluated the integrity of vasculature in the lower extremities. After extensive evaluation, we classified the patients into eight groups (category 0,1,2,3,4A,4B,5,6). The result of this study suggested that the Semmes-Weinstein monofilament test, Rydel-Seiffer graduated tuning fork test, and checking the ankle/brachial index were simple techniques for evaluating pathologic change in the diabetic foot by office screening, and that this screening based on treatment-oriented classification helps to reduce pedal complications in a diabetic population.

Multichannel, direct-reading spectrograph attachment

An instrument is described which provides a multichannel direct-reading capability for photoelectric spectrographic detection. The important feature of the instrument is the ability of the user to select at will any combination of channels for position adjustment and to move these while preserving the optical integrity of the enclosure. Photomultipliers are used and the results of performance tests are described.