PubMed Health⌕ Search

Biomedical subjects

H G Alexander

Publications and source records attributed to H G Alexander.

6 recordsLinked to original sources
PubMed2001

Development and characterization of tissue-engineered aortic valves.

Tissue-engineered aortic valves, known as recellularized heart valves, were developed by seeding human neonatal fibroblasts onto decellularized, porcine aortic valves. Recellularized heart valves were cultured up to 8 weeks in a novel bioreactor that imposed dynamic pulsatile fluid flow to expose the dermal fibroblasts to mechanical forces. Our data showed that, under static or dynamic flow conditions, dermal fibroblasts attached to and migrated into the decellularized, porcine valve scaffolding. The human cells remained viable as indicated by MTT viability staining. Gradual colonization of the decellularized porcine scaffolding by the human dermal fibroblasts was shown histologically by hematoxylin & eosin staining, immunocytochemically using a monoclonal antibody directed against prolyl-4-hydroxylase (an intracellular enzyme expressed by human fibroblasts synthesizing collagen), and quantitative digital image analyses. Thymidine and proline radiolabeled analog studies at 1, 2 and 4 weeks of individual leaflets cultured statically demonstrated that the human fibroblasts were mitotic and synthesized human extracellular matrix proteins, thereby supplementing the existing porcine matrix. The overall approach results in a heart valve populated with viable human cells. In the development of valves that perform in a similar manner as natural biological structures, this approach may present some unique benefits over current medical therapies.

Animals↗
PubMed1992

Fascial planes within subcutaneous fat in humans.

We have used B-mode (brightness-mode) ultrasound to investigate the fascial planes within subcutaneous fat at the triceps and abdominal sites in a group of 17 women attending a weight control group over a 12 month period. In most subjects there was a single intralipid fascial plane at each site. As the thickness of adipose tissue increased, most of the change at the abdominal site was in the deep rather than the superficial layer of fat. At the triceps site both deep and superficial layers increased. Our findings confirm the presence of two different layers in human subcutaneous fat at the triceps and abdominal sites. These layers have been shown to be functionally different in animals and our study supports this in humans at the abdominal site.

Abdomen↗
PubMed1991

The scintigraphic "duodenal cut off sign" in acute pancreatitis.

Acute pancreatitis is a dreaded complication of biliary calculus disease, and several radiographic signs have been reported in association with this condition. We report a new sign demonstrated on hepatobiliary scintigraphy, the duodenal cut off sign, seen in a patient being evaluated for stone disease and later found to have acute pancreatitis. Hepatobiliary scans are commonly performed during the initial evaluation of patients with suspected calculus disease, and visualization of this sign may indicate to the clinician that he is dealing with a more serious condition.

Acute Disease↗
PubMed1989

A meconium suctioning device that is safe and practical.

Immediate suctioning of meconium from the trachea of newborns is believed to be an effective method for preventing or minimizing the meconium aspiration syndrome. Recently, however, the possibility of transmitting disease from the newborn to the physician or vice versa, while using the standard technique of direct oral suction (through a surgical mask), has been stressed. This has prompted the development of alternative methods for suctioning the newborn's trachea. These methods, while eliminating the possibility of disease transmission, create other problems. We, therefore, devised a technique for tracheal suctioning using inexpensive, readily available materials that is not only safe and effective in suctioning meconium but is also practical and easy to perform.

Humans↗