A novel mouse model of hindlimb joint contracture with 3D-printed casts

Stiff joints formed after trauma, surgery or immobilization are frustrating for surgeons, therapists and patients alike. Unfortunately, the study of contracture is limited by available animal model systems, which focus on the utilization of larger mammals and joint trauma. Here we describe a novel mouse-based model system for the generation of joint contracture using 3D-printed clamshell casts. With this model system we are able to generate both reversible and irreversible contractures of the knee and ankle. Four- or 8-month-old female mice were casted for either 2 or 3 weeks before liberation. All groups formed measurable contractures of the knee and ankle. Younger mice immobilized for less time formed reversible contractures of the knee and ankle. We were able to generate irreversible contracture with either longer immobilization time or the utilization of older mice. The contracture formation translated into differences in gait, which were detectable using the DigiGait® analysis system. This novel model system provides a higher throughput, lower cost and more powerful tool in studying the molecular and cellular mechanisms considering the large existing pool of transgenic/knockout murine strains.

Upper Extremity Injuries in CrossFit Athletes-a Review of the Current Literature

PURPOSE OF REVIEW

Cross-discipline fitness, or CrossFit, has exploded in popularity during the last two decades. During this time, there have been a high volume of patients presenting to clinicians with a wide range of associated injuries. Given the high intensity, high repetition, and competitive nature of CrossFit training and competition, athletes are vulnerable to injury, particularly upper extremity injury. The rate of injury to the shoulder, elbow, and wrist in CrossFit is higher when compared to traditional weight-training and more comparable to elite-level gymnastics and Olympic-style lifting. Due to the growing popularity of CrossFit-style exercise and the relatively high rate of injury among its participants, clinicians are likely to encounter these athletes. The purpose of this review is to familiarize clinicians with CrossFit and the associated injuries they will likely encounter.

RECENT FINDINGS

The medical literature focusing on CrossFit has demonstrated exponential growth, with the first article published in 2012 and 59 articles published in 2020. Although the body of literature is growing, there are no high-level studies focusing on CrossFit. The literature mainly consists of level IV and V studies, primarily consisting of case reports and case series. Recent studies have proven that CrossFit athletes are vulnerable to high rates of upper extremity injury and a few studies have identified risk factors for injury. Future high-level research is required to study modifiable risk factors, diagnostic criteria, and treatment options for these high-risk athletes in order to improve the safety of their sport. The CrossFit body of research is limited to level IV and V studies; however, the literature is clear, CrossFit athletes face a high rate of upper extremity injury. For this reason, clinicians must be familiar with CrossFit and its associated pathology. The goal of this review is to familiarize clinicians with CrossFit and the associated pathologies they will likely encounter.

Water-Soluble Nanoconjugate for Enhanced Cellular Delivery of Receptor-Targeted Magnetic Resonance Contrast Agents

ProGlo is an efficient steroid receptor-targeted magnetic resonance (MR) imaging contrast agent (CA). It has been shown to bind to the progesterone receptor (PR) and produce enhanced image contrast in PR-positive cells and tissues in vitro and in vivo. However, the hydrophobicity of the steroid targeting domain of ProGlo (logP = 1.4) limits its formulation and delivery at clinically relevant doses. In this work, a hydrophobic moiety was utilized to drive efficient adsorption onto nanodiamond (ND) clusters to form a water-soluble nanoconstruct (logP = -2.4) with 80% release in 8 h under biological conditions. In cell culture, the ND-ProGlo construct delivered increased concentrations of ProGlo to target cells compared to ProGlo alone. Importantly, these results were accomplished without the use of solvents such as DMSO, providing a significant advance toward formulating ProGlo for translational applications. Biodistribution studies confirm the delivery of ProGlo to PR(+) tissues with enhanced efficacy over untargeted controls. These results demonstrate the potential for a noncovalent ND-CA construct as a general strategy for solubilizing and delivering hydrophobic targeted MR CAs.

Nanodiamond-Gadolinium(III) Aggregates for Tracking Cancer Growth In Vivo at High Field

The ability to track labeled cancer cells in vivo would allow researchers to study their distribution, growth, and metastatic potential within the intact organism. Magnetic resonance (MR) imaging is invaluable for tracking cancer cells in vivo as it benefits from high spatial resolution and the absence of ionizing radiation. However, many MR contrast agents (CAs) required to label cells either do not significantly accumulate in cells or are not biologically compatible for translational studies. We have developed carbon-based nanodiamond-gadolinium(III) aggregates (NDG) for MR imaging that demonstrated remarkable properties for cell tracking in vivo. First, NDG had high relaxivity independent of field strength, a finding unprecedented for gadolinium(III) [Gd(III)]-nanoparticle conjugates. Second, NDG demonstrated a 300-fold increase in the cellular delivery of Gd(III) compared to that of clinical Gd(III) chelates without sacrificing biocompatibility. Further, we were able to monitor the tumor growth of NDG-labeled flank tumors by T1- and T2-weighted MR imaging for 26 days in vivo, longer than was reported for other MR CAs or nuclear agents. Finally, by utilizing quantitative maps of relaxation times, we were able to describe tumor morphology and heterogeneity (corroborated by histological analysis), which would not be possible with competing molecular imaging modalities.

Diamond-lipid hybrids enhance chemotherapeutic tolerance and mediate tumor regression

Self-assembled nanodiamond-lipid hybrid particles (NDLPs) harness the potent interaction between the nanodiamond (ND)-surface and small molecules, while providing a mechanism for cell-targeted imaging and therapy of triple negative breast cancers. Epidermal growth factor receptor-targeted NDLPs are highly biocompatible particles that provide cell-specific imaging, promote tumor retention of ND-complexes, prevent epirubicin toxicities and mediate regression of triple negative breast cancers.

A robust Monte Carlo model for the extraction of biological absorption and scattering in vivo

We have a toolbox to quantify tissue optical properties that is composed of specialized fiberoptic probes for UV-visible diffuse reflectance spectroscopy and a fast, scalable inverse Monte Carlo (MC) model. In this paper, we assess the robustness of the toolbox for quantifying physiologically relevant parameters from turbid tissue-like media. In particular, we consider the effects of using different instruments, fiberoptic probes, and instrument-specific settings for a wide range of optical properties. Additionally, we test the quantitative accuracy of the inverse MC model for extracting the biologically relevant parameters of hemoglobin saturation and total hemoglobin concentration. We also test the effect of double-absorber phantoms (hemoglobin and crocin to model the absorption of hemoglobin and beta carotene, respectively, in the breast) for a range of absorption and scattering properties. We include an assessment on which reference phantom serves as the best calibration standard to enable accurate extraction of the absorption and scattering properties of the target sample. We found the best reference-target phantom combinations to be ones with similar scattering levels. The results from these phantom studies provide a set of guidelines for extracting optical parameters from clinical studies.

Effect of adrenalin, adrenochrome, and adrenolutin on connexin proteins in the cardiovasculature

Reported myocardial pathology resulting from increased levels of catecholamines in vivo has led us to investigate the effect of adrenalin on the gap junction proteins connexin 40 (Cx40) and Cx43 and the possible relationship to vascular toxicity. Adrenalin and its known metabolites, adrenochrome and adrenolutin, were used in this study. Utilizing the A7r5 rat aortic cell line, we evaluated the effects of adrenalin, adrenochrome, and adrenolutin on the expression and function of connexin 40 and 43 that are present in both cardiac and vascular tissues.

Gap junctions in vascular tissues. Evaluating the role of intercellular communication in the modulation of vasomotor tone

Integration and coordination of responses among vascular wall cells are critical to the local modulation of vasomotor tone and to the maintenance of circulatory homeostasis. This article reviews the vast literature concerning the principles that govern the initiation and propagation of vasoactive stimuli among vascular smooth muscle cells, which are nominally the final effectors of vasomotor tone. In light of the abundance of new information concerning the distribution and function of gap junctions between vascular wall cells throughout the vascular tree, particular attention is paid to this integral aspect of vascular physiology. Evidence is provided for the important contribution of intercellular communication to vascular function at all levels of the circulation, from the largest elastic artery to the terminal arterioles. The thesis of this review is that the presence of gap junctions, in concert with the autonomic nervous system, pacemaker cells, myogenic mechanisms, and/or electrotonic current spread (both hyperpolarizing and depolarizing waves through gap junctions), confers a plasticity, adaptability, and flexibility to vasculature that may well account for the observed diversity in regulation and function of vascular tissues throughout the vascular tree. It is hoped that the summary information provided here will serve as a launching pad for a new discourse on the mechanistic basis of the integrative regulation and function of vasculature, which painstakingly accounts for the undoubtedly complex and manifold role of gap junctions in vascular physiology/dysfunction.

Gap junction function in vascular smooth muscle: influence of serotonin

In this study we examined the effects of serotonin (5-hydroxytryptamine, 5-HT) on the function of gap junctions between smooth muscle cells isolated from human and pig coronary and rat mesentery arteries and between A7r5 cells (cell line derived from embryonic rat aorta). Mesentery and pig coronary cells expressed connexin (Cx) 43, and human coronary cells expressed Cx40. Mesentery and pig coronary cells each exhibited a single gap junction channel population with unitary conductances of 75 and 59 pS, respectively. Human coronary cells exhibited two channel populations with unitary conductances of 51 and 107 pS. The A7r5 cells express Cx40 and Cx43 and exhibit three channel populations with unitary conductances of 70, 108, and 141 pS. Under control conditions, junctional conductance between the four cell types ranged from 11 to 20 nS. During maximal stimulation with 5-HT (1-10 microM), junctional conductance increased (29-75%) in all four cell types. The unitary conductance profiles in the rat mesentery and pig coronary cells were unaffected by 5-HT, suggesting that the observed increase in macroscopic conductance reflects an increase in open probability. Unitary conductances were also unaffected in the human coronary and A7r5 cells. However, there was a reduced frequency of the 105-pS channel in the human coronary cells and of the 70- and 141-pS channels in the A7r5 cells. These changes in the relative frequency histograms suggest that the open probabilities of the various channel types are differentially affected by the 5-HT treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Selective block of gap junction channel expression with connexin-specific antisense oligodeoxynucleotides

Gap junctions in vascular smooth muscle provide a cell-to-cell conduction pathway that may contribute to regulation and coordination of changes in vascular tone. A7r5 cells, a cell line derived from embryonic rat aorta, express connexin 43 (Cx43) and connexin 40 (Cx40). Gap junction channels with three distinct unitary conductances (70, 108, and 141 pS) were observed in these cells. Events of each channel type were equally common, with an approximate frequency of 30-35%; however, the frequency at which each channel type was observed in individual cell pairs ranged between 10 and 65%. Treatment of the cells for 24-72 h with an antisense oligodeoxynucleotide (ODN) to Cx43 reduced the relative frequency of the 108- and 141-pS channel events, whereas comparable treatment with antisense Cx40 ODN reduced the frequency at which 70-pS channel events were observed. The simplest explanation of these findings is that Cx43 forms the 108- and 141-pS channels, whereas Cx40 forms the 70-pS channels in A7r5 cells.

Oleic acid differentially affects gap junction-mediated communication in heart and vascular smooth muscle cells

The effects of oleic acid (OA) on gap junction-mediated intercellular communication between A7r5 cells and neonatal rat cardiac myocytes were determined. In A7r5 cells the extent of dye coupling was influenced in a biphasic manner by increasing concentrations of OA. Low concentrations of OA (0.1-1 microM) reduced the incidence of dye coupling from 90% (in control cells) to approximately 50%. Further increases in OA concentration, up to 100 microM, had no further effect on extent of dye coupling. In contrast, dye coupling between cardiac myocytes was reduced to near zero levels in a linear fashion by 1-25 microM OA. Whereas high OA concentrations reduce junctional conductance (gj) between heart cells to zero [J. M. Burt, K. D. Massey, and B. N. Minnich. Am. J. Physiol. 260 (Cell Physiol. 29): C439-C448, 1991], gj between A7r5 cells was decreased by a maximum of 45% by OA. These differences in OA sensitivity between the two cell types were not explained by differences in the rate or magnitude of OA uptake by the cells or by differences in the fraction of incorporated OA accessible to albumin washout, i.e., the plasma membrane fraction. Instead, the activity of the individual channel types exhibited different sensitivities to OA. In the presence of increasing concentrations of OA, the activities of first the 70-pS channel population [composed of connexin40 (Cx40)] and then the 108-pS channel population (composed of Cx43) were diminished, leaving predominantly the 140-pS channels (composed of Cx43) at high OA concentrations. The uncoupling effects of OA in both cell types could be reversed by washout with albumin-containing solution; however, higher concentrations of albumin and more vigorous wash conditions were required for full recovery in the A7r5 cells. In addition, albumin also reversed the effects of OA on channel activity. These data suggest that OA binds with greater affinity to the 70- vs. 108- or 140-pS channels and associated with binding is reduced channel activity.

Characterization of gap junction channels in A7r5 vascular smooth muscle cells

Recent evidence suggest that coordination of blood flow in the microcirculation involves cell-to-cell coupling via gap junctions. In this study, using A7r5 cells as a model of vascular smooth muscle, we have characterized the gap junctions in terms of the unitary conductances of the observed channels, the responses to second messengers, and subunit protein composition. The cells were typically well coupled several hours after plating, with junctional conductances on the order 20-40 nS. Channels with mean conductances of 36 and 89 pS were observed in low-conductance cell pairs and in cell pairs whose macroscopic conductance was reduced by exposure to halothane. Connexin43 was the only known gap junction sequence detected by Northern blots (low and high stringency), immunoblots, or immunohistochemical studies. Junctional conductance was reduced 15% by 8-bromoadenosine 3',5'-cyclic monophosphate; 8-bromoguanosine 3',5'-cyclic monophosphate had no effect. The results suggest that connexin43 can form stable channels of at least two distinct conductances and gap junctions with differing responses to second messengers.

High-performance liquid chromatographic method for isolating coprostanol from sediment extracts

We report a rapid, largely automated high-performance liquid chromatographic (HPLC) method, which uses an HPLC column packed with alkylnitrile-substituted secondary alkylamine (aminocyano) bonded phase, to isolate coprostanol from interfering compounds in sediment extracts. Coprostanol is then quantitated, as the trimethylsilyl ether, by gas chromatography with flame ionization detection. Results from using the HPLC method to analyze a sediment reference material for coprostanol were statistically comparable to a previously used gravity-flow column method. We also report the coprostanol concentrations in several sediment samples from the California coast which reflect a range of sewage contamination (62-15,000 ng/g).

High-performance liquid chromatographic method for isolating organic contaminants from tissue and sediment extracts

Interest in the assessment of the anthropogenic contamination of the marine environment has accelerated in recent years. Existing methods to analyze environmental samples (e.g., sediments or tissues) for trace amounts of organic contaminants such as aromatic hydrocarbons and chlorinated compounds are tedious and costly. We report a rapid, efficient high-performance liquid chromatography (HPLC) procedure which uses a size-exclusion column to separate the analytes of interest from interfering compounds in the sample matrix. Analytical results from the HPLC method were, in general, comparable to a gravity-column method which had been used for several years. The HPLC method had several other advantages: improved precision; the ability to monitor chromatographic conditions; the potential for automating analyses; and reduced consumption of solvents and other materials.

Adult leukemias

Over the past several years, advances have been made in the classification, diagnosis and therapy of the adult leukemias. The overall prognosis and quality of life have improved greatly, especially for patients with acute nonlymphoblastic leukemias. Some of the advances are described in this article. The importance of the clinical, laboratory and diagnostic tests for acute, chronic granulocytic and chronic lymphocytic leukemia are stressed. The therapy and prognosis for patients with the various types of leukemia are also described.

Effect of intermittent infusions of glucose-containing crystalloid cardioplegic solution on myocardial tissue lactic acid and recovery of contractility

The objective of this study was to determine the effects of single or intermittent infusions of cardioplegic solution with glucose (5 gm/L) or without glucose on myocardial tissue lactic acid and recovery of myocardial contractility following 80 minutes of total ischemia at 28 degrees C in the isolated, blood-perfused, beating rabbit heart. Ischemia without cardioplegia increased tissue lactic acid (6.79 mg/gm tissue) above the control value (0.9 mg/gm tissue), p less than 0.0025). Lactic acid following single infusions with (4.19 mg/gm tissue) or without glucose (3.67 mg/gm tissue) was significantly greater (p less than 0.0025) than tissue lactic acid following intermittent infusions with (1.06 mg/gm tissue) or without glucose (1.05 mg/gm tissue). Cardioplegic arrest in all cases significantly decreased tissue lactate accumulation when compared to arrest without cardioplegia (p less than 0.01). The decrease in myocardial contractility demonstrated when no cardioplegic protection was employed (86% recovery) was completely eliminated (100% recovery) with a single-bolus infusion of cardioplegic solution containing glucose (p less 0.025). Intermittent infusions of cardioplegic solution containing glucose (92% recovery) and single infusions without glucose (93% recovery) also improved recovery of contractility following ischemia, but the results were not statistically significant.

Delayed recovery following hypothermic arrest in rabbit myocardium

The purpose of this investigation was to determine the relationship between the duration of myocardial ischemia at 15 degrees C and the time required for the myocardium to recover maximum contractile function following the ischemia. The isolated blood perfused rabbit heart was used as a model of myocardial ischemia. Hearts from 22 New Zealand white rabbits were divided into four groups. In Group I seven hearts were subjected to 15 minutes of ischemia at 15 degrees C. In Group II five hearts were subjected to 30 minutes of ischemia at 15 degrees C. In Group III and IV the ischemia time was extended to 60 and 120 minutes, respectively. Following the ischemia each heart was reperfused at normothermia and papillary muscle contractility was measured and used as an index of myocardial recovery. Hearts in Group I recovered their maximum contractile function after an average of 22.5 minutes. Those in Groups II, III, and IV were fully recovered after 31.7, 38.2, and 45.5 minutes, respectively. The study indicates that the time required for the maximum recovery of myocardial contractility following myocardial ischemia increases at a decreasing rate with an increase in the duration of the ischemia at 15 degrees C.