Biomechanical and Biological Characterization of XGel, a Human-Derived Hydrogel for Stem Cell Expansion and Tissue Engineering

Hydrogels are 3D scaffolds used as alternatives to in vivo models for disease modeling and delivery of cells and drugs. Existing hydrogel classifications include synthetic, recombinant, chemically defined, plant- or animal-based, and tissue-derived matrices. There is a need for materials that can support both human tissue modeling and clinically relevant applications requiring stiffness tunability. Human-derived hydrogels are not only clinically relevant, but they also minimize the use of animal models for pre-clinical studies. This study aims to characterize XGel, a new human-derived hydrogel as an alternative to current murine-derived and synthetic recombinant hydrogels that features unique physiochemical, biochemical, and biological properties that support adipocyte and bone differentiation. Rheology studies determine the viscosity, stiffness, and gelation features of XGel. Quantitative studies for quality control support consistency in the protein content between lots. Proteomics studies reveal that XGel is predominantly composed of extracellular matrix proteins, including fibrillin, collagens I-VI, and fibronectin. Electron microscopy of the hydrogel provides phenotypic characteristics in terms of porosity and fiber size. The hydrogel demonstrates biocompatibility as a coating material and as a 3D scaffold for the growth of multiple cell types. The results provide insight into the biological compatibility of this human-derived hydrogel for tissue engineering.

The role of inflammation-related genes in osteoarthritis

In this review article we examine the role of inflammation-related genes in osteoarthritis (OA) from the perspective of genetics, epigenetics and gene expression. There have been great strides in such genomic analyses of OA in recent years thanks to the study of adequately powered patient cohorts, the detailed analysis of candidate genes, and the application of genome-wide approaches. These have led to some unexpected and therefore exciting discoveries, implicating pathways that would not necessarily have been predicted to have a role in this common arthritis. Inflammatory-related genes sit firmly in the candidate camp based on prior observations that the OA disease process can have an inflammatory component. What is clear from the genetic studies published to date is that there is no compelling evidence that DNA variation in inflammatory genes is an OA risk factor. This conclusion may of course change as ever more powerful association studies are conducted. There is, however, compelling evidence that epigenetic effects involving inflammatory genes are a component of OA and that alteration in the expression of these genes is also highly relevant to the disease process. We may in fact be close to demonstrating, at the genomic level, a clear separation of OA patients into those in whom inflammation is a key driver of the disease and those in whom it is not. This has obvious implications for the design of trials of novel OA interventions and may also guide the intelligent re-purposing of anti-inflammatory therapies.

Stereotactic breast biopsy: a six-year surgical experience

A retrospective review was done of all stereotactic breast biopsies performed at the Central Baptist Hospital Breast Center from February 1994 through December 1999. A total of 1,080 biopsies were performed in 1,026 patients, all by surgeons working independently. Masses were biopsied in 54% and calcifications in 40%. Eighteen percent of biopsies were malignant. The most common benign diagnosis was fibrocystic disease (72%), followed by fibroadenoma (19%), lymph node (2%), and papilloma (2%). The most common malignant diagnosis was invasive ductal carcinoma (40%) followed by ductal carcinoma in situ (32%) and mixed invasive and in situ ductal carcinoma (19%). A prebiopsy BI-RADS mammographic Category III was associated with a 2% incidence of malignancy; Category IV--17%; Category V--90%. Atypical ductal hyperplasia on stereotactic biopsy was upgraded to a malignant diagnosis after reexcision in 19% of the cases. The false-negative rate was 0.4% (sensitivity 99%) and the complication rate was 3%, mostly related to bleeding. Stereotactic biopsy is a safe and accurate technique for the minimally-invasive diagnosis of abnormal mammograms.

Breast conservation versus mastectomy: patient preferences in a community practice in Kentucky

Recent studies have indicated a relatively low rate of breast-sparing surgery for carcinoma in the Southeastern United States. From 1987 through 1991, 289 patients from Eastern and Central Kentucky with breast carcinoma were treated by the authors. Despite being fully informed of treatment options of breast cancer, 82% of patients with stage II disease or less and no medical contraindications to breast conservation preferred mastectomy. Overall, 10% of patients underwent breast-sparing surgery, although this figure had risen to 20% by 1991. The most frequent reasons for preference of mastectomy were fear and inconvenience of radiotherapy and a perception that survival would be diminished if mastectomy was not done.

Health maintenance issues of the elderly. Nutrition

Although we are on steep learning curve as far as the exact relationship between nutrition and disease prevention is concerned, evidence is accumulating on the role of body mass index and mortality, protein deficiency and decreased ability to fight infection, effect of fiber intake on cholesterol and glucose metabolism, hyperlipidemia and atherosclerosis, and inadequate calcium intake in osteoporosis. Screening for nutritional disorders includes identifying those with risk factors of being female, black, poor, or institutionalized. Evidence of weight change, dietary idiosyncracies, nutrient deficiency, and laboratory tests can be helpful. Treatment should be tailored to the individual and be specific for suspected deficiencies. Attention to calories, protein, and calcium are paramount.

Adenocarcinoma of the lower esophagus. A disease primarily of white men with Barrett's esophagus

Sex and racial predilection, social history, and histology were analyzed in a biopsy-proven adenocarcinoma of the lower esophagus/esophagogastric junction collected over a 5-year period in two teaching institutions with different patient populations. Adenocarcinoma occurred in 11% of patients with biopsy-proven esophageal cancer. The disease occurred only in males at one center, and in a 7:1 ratio of males to females at the other center. Clear racial predilection was seen, since 12 of 13 patients with adenocarcinoma of the esophagus were white, whereas less than 20% of patients with squamous carcinoma of the esophagus were white. The finding of Barrett's epithelium in eight of the 13 cases strongly supports the theory that in white males, Barrett's epithelium is a precursor lesion of adenocarcinoma of the esophagus/esophagogastric junction.

Chronic liver disease following community-acquired non-A, non-B hepatitis

Chronic non-A, non-B hepatitis occurring in an urban American population was identified in 23 patients followed for more than six months after the onset of acute hepatitis. Eight of the 23 patients subsequently developed normal aminotransferase levels a mean of 12.3 months after the onset of hepatitis. Liver biopsies were obtained from 9 of the remaining 15 patients. Eight biopsies revealed abnormalities consistent with chronic persistent hepatitis. One revealed chronic active hepatitis. The probable source of hepatitis included blood transfusions in 4%, intravenous drugs in 43%, personal contact in 4%, and no known source in 48%. Normalization of aminotransferase activity could not be predicted by initial symptoms, physical findings, or laboratory values. This study suggests that the chronic liver disease following community-acquired non-A, non-B hepatitis is frequent and may have a benign course.

Hepatic encephalopathy

In summary, then, it can be said that hepatic encephalopathy is a process caused by the underlying inability of the certain products to be metabolized in a damaged liver. These products lead to altered neurotransmission with the resulting neurologic finding of altered affect, confusion, somnolence, or coma. Augmentation of the neurologic deficit occurs when the patient suffers additional metabolic insults. Treatment of the patient with hepatic encephalopathy requires careful monitoring and aggressive therapy for those factors known to precipitate encephalopathy, as well as treatment of the underlying hepatic process and encephalopathy.

The spectrum of carcinoma arising in Barrett's esophagus. A clinicopathologic study of 26 patients

The clinical and pathologic features of carcinoma arising in Barrett's esophagus were studied in resection specimens from 26 patients. White males predominated (73%). A history of symptomatic gastroesophageal reflux was frequently absent, being elicited in only eight of 14 patients (57%) with a carefully obtained history at the time of presentation with carcinoma. Survival was relatively short with a median survival of 23 +/- 5 months, and only three patients had a disease-free survival longer than 2 years. A pathologic spectrum of carcinoma was found: differentiation ranged from well to poorly differentiated in the 20 patients with a single adenocarcinoma; two separate carcinomas were found in four patients; and a spectrum of differentiation in a single tumor was found in the other two cases, one an adenocarcinoid tumor and the other an adenosquamous carcinoma. The tumors were generally far advanced, with extension through the esophageal wall in 23 of 26 cases (88%) and metastases to lymph nodes in 17 of 24 cases (71%). Epithelial dysplasia, including carcinoma in situ in some cases, was found in Barrett's mucosa adjacent to the tumor in all 26 patients. Our findings suggest that a surveillance program for dysplasia in patients known to have Barrett's esophagus is warranted in an attempt to improve the outcome. However, the impact of surveillance on the incidence of Barrett's carcinoma may be lessened by its frequent occurrence in patients with asymptomatic gastroesophageal reflux.

Substernal gastric bypass for palliation of esophageal carcinoma: rationale and technique

A review of sixteen consecutive patients who underwent substernal gastric bypass (SSGB) for middle and upper thoracic esophageal cancer is presented. All patients were alcoholics and heavy smokers with significant medical risk factors. All had locally advanced, long, circumferential, obstructing lesions with regional metastases. The operative mortality rate was 36% in this group of high-risk patients with advanced disease. This high mortality rate may decrease with the modifications discussed. The previously described technique of SSGB is detailed with special reference to a modification for widening the thoracic inlet. The palliation afforded was excellent in all survivors, and the median survival time was a surprisingly long 10 months. Alternative approaches are discussed in a review of the literature. SSGB provides quite possibly the superior approach for palliative management of these difficult lesions.

Selective chemical hepatic sympathectomy in the dog

Intraportal injection of 6-hydroxydopamine (6-OHDA) was used to produce selective hepatic sympathectomy in the dog. Previously reported techniques for 6-OHDA induced hepatic sympathectomy in rats and cats were modified considerably using alpha and beta adrenergic blocking agents to prevent the otherwise intense and fatal sympathomimetic response which has prevented adaptation of the intraportal 6-OHDA injection for dogs. After 6-OHDA injection, histofluorescent staining demonstrated loss of hepatic adrenergic nerves with preservation of normal adrenergic innervation in the heart and pancreas. Tyramine iv was used to further document functional integrity of peripheral sympathetic mechanisms. This technique provides a useful model for evaluation of sympathetic nervous system mediated changes in hepatic metabolic function associated with the neuroendocrine response to hemorrhage in the classic dog model.

Increasing frequency of esophageal cancer among black male veterans

Between the years of 1975 and 1979, the frequency of diagnosis of esophageal cancer has doubled at the Baltimore VA Medical Center due to a rapid increase of esophageal cancer among black males. This increase was not related to increased yearly hospital admission rates, percentage of black patients admitted yearly, or increased use of the hospital for chronic disease processes. Detailed chart review and comparison with consecutive medical admissions as controls revealed heavy alcohol use and urbanization to be risk factors experienced more frequently by black than white male veterans. A serious question needs to be quickly answered: Does the rise of esophageal cancer at the Baltimore VAMC reflect a rise among black males only in Baltimore or does it reflect a rise nationwide among black males with a history of previous employment in the armed forces?

Surgery for morbid obesity: indications, complications, alternatives

Morbid obesity (100 pounds over ideal body weight) carries with it numerous medical complications and increased mortality which can be improved by weight loss. Medical treatment of obesity is usually not successful, and jejunoileal bypass surgery often produces considerable chronic morbidity which seriously compromises its benefits. Gastric bypass is equally effective and avoids the most severe long-term complications of jejunoileal bypass, but has a higher operative morbidity. Gastric plication will perhaps offer the least operative and chronic morbidity, though few long-term statistics are as yet available.

Disulfiram-associated hypercholesterolemia

The rat model is used to verify disulfiram-associated hypercholesterolemia and to determine a mechanism of action. Administration of disulfiram 15 mg/kg/day for 3 wk is associated with a 25% increase in serum cholesterol which is reversible with discontinuance of the drug. The hypercholesterolemia is due in part to a fourfold increase in activity of hepatic HMG-CoA reductase, the rate-limiting step in cholesterol biosyntheses.

Fulminant hepatic failure and hepatic encephalopathy

Fulminant hepatic failure implies either acute massive destruction of liver tissue or another process that causes rapid deterioration in function of a previously normal liver. The diagnosis in children needs to be differentiated from hepatic failure that occurs as a complication of underlying congenital, anatomical, and metabolic abnormalities.

Deficiency of fat soluble vitamins after jejunoileal bypass surgery for morbid obesity

Significant vitamin A, E, or 25-hydroxy D deficiency occurred in 76% of 40 patients studied up to 6 years after jejunoileal bypass surgery for morbid obesity. Vitamin A was significantly lower in those who had lost 30% of their initial weight than in those who had lost less weight; however, there was no correlation of vitamin A, E, or D levels, time elapsed since surgery, or with daily intake of vitamins as subnormal values were found despite multivitamin supplementation and consumption of twice the recommended daily allowance of vitamin A. Functional derangement of retinal adaptation to darkness secondary to vitamin A deficiency was found in four of nine stable, healthy patients studied at least 18 months after surgery. There was no linear relationship between vitamin A levels and dark adapted final thresholds or with serum albumin, prothrombin time, or degree of steatorrhea. Three patients with abnormal adapted final thresholds were treated with vitamin A. Total daily intake of up to 65,000 IU of vitamin A daily for several months resulted in normalization of function in all.

Cholecystokinin cholecystography in the diagnosis of gallbladder disease

Twenty-six patients who had typical symptoms of biliary tract disease, e.g. postprandial right upper quadrant pain, nausea and vomiting, fatty food intolerance and flatulence and who had had two or more normal oral cholecystograms were subjected to cholecytokinin cholescystography. Ten patients showed a normal response to the intravenous administration of cholecystokinin, namely prompt and complete emptying of the gallbladder without producing any adverse reaction or symptoms. Sixteen patients demonstrated either no contraction or incomplete contraction of the gallbladder in response to cholecystokinin; several patients had moderate contraction of the gallbladder accompanied by symptoms of biliary colic. This latter group underwent cholecystectomy and operative cholangiography. Fifteen of the 16 patients are asymptomatic or improved, and only one patient continues to have symptoms. All removed gallbladders had histologic evidence of chronic cholecystitis. It is concluded that in some individuals with continuing symptoms suggesting gallbladder disease but normal oral cholecystograms, cholecystokinin cholecystography may be helpful in identifying physiologic dysfunction of the gallbladder.