Biomedical subjects

J W Fries

Publications and source records attributed to J W Fries.

25 records · Page 2Linked to original sources

PubMed1987

Characterization of an inbred strain of the SENCAR mouse that is highly sensitive to phorbol esters.

An inbred strain of SENCAR mice was developed that is more sensitive to two-stage skin carcinogenesis protocols than the outbred parental stock. These mice, registered as SSIN/UTSP, were compared to the SENCAR in initiation-promotion protocols using the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) twice weekly for 22 weeks at dose levels of 0.5, 1.0 and 2.0 micrograms. With 0.5 microgram of TPA, the number of papillomas in the SSIN was 3-fold higher than in the SEN-CAR; the tumor incidence was 100 versus 60%, respectively. Similar, although less dramatic, results were found with 1.0 and 2.0 micrograms of TPA. In two-step promotion protocols using TPA twice weekly for 2 weeks and 2 micrograms mezerein twice weekly for 15 weeks the SSIN produced approximately 50% more tumors than the SENCAR at 0.5 microgram of TPA. At 2 micrograms of TPA the tumor response between the two mice was not significantly different. Epidermal hyperplasia was considerably greater in the SSIN at 0.5 microgram of TPA as was ornithine decarboxylase activity. These TPA-sensitive inbred mice should be useful in investigations on the biochemical and genetic factors involved in skin tumor promotion.

Animals↗

PubMed1986

Malignant progression of mouse skin papillomas treated with ethylnitrosourea, N-methyl-N'-nitro-N-nitrosoguanidine, or 12-O-tetradecanoylphorbol-13-acetate.

Mouse skin tumors were induced by a single topical application of 7,12-dimethylbenzanthracene (DMBA), followed by biweekly promotion with 12-O-tetradecanoylphorbol-13-acetate (TPA). After 20 weeks of promotion, mice were treated twice weekly for 2 weeks with either ethylnitrosourea (ENU), N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or TPA. Thereafter all groups were treated biweekly with TPA. The ENU-treated group had a higher percentage of animals with carcinomas and developed 217% more cumulative carcinomas per group than TPA-treated controls. The percentage of mice with carcinomas and the cumulative number of carcinomas per group in MNNG-treated mice was higher than TPA-treated controls but was less than ENU-treated mice. The ratio of cumulative carcinomas to cumulative papillomas in ENU treated, MNNG-treated and TPA-treated mice was 16%, 9% and 6%, respectively. Histological examination of tumors remaining at the termination of the experiment revealed the presence of keratoacanthomas, some of which stained positive for gamma-glutamyltransferase (GGT), in the ENU-treated and MNNG-treated, but not the TPA-treated groups. The fact that no new papillomas developed during the progression stage indicated that enhanced carcinogenesis resulted from the progression of pre-existing tumors. Enhanced progression of benign skin tumors in mice by only a few treatments of an agent may serve as a potential model for studies into the mechanisms and the inhibition of malignant progression. The model also allows for a comparison of the potency of agents in enhancing malignant progression.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1986

Allogeneic transplantation of normal epidermal cells and squamous cell carcinomas in SENCAR mice.

A method used in our laboratory for the transplantation of single cell suspensions of epidermis and skin carcinomas is described. Silicone chambers were placed into a subcutaneous granulation tissue formed by the implantation of a glass disk. The skin was closed on top of the chamber by using Michael autoclips. Cells were injected 24 to 48 hr later through the skin using a syringe and needle. The neoformation of epithelia with adnexa was observed when newborn epidermal cells were injected. When a fresh cell suspension of squamous cell carcinoma was used, a typical differentiated carcinoma was formed within 2 to 4 weeks. However, after 4 weeks, some of the grafts showed mild signs of rejection. The technique described is a useful system to transplant squamous cell carcinomas and can also be used as a rapid assay for malignancy.

Animals↗

PubMed1986

Enhanced malignant progression of mouse skin tumors by the free-radical generator benzoyl peroxide.

Chemical carcinogenesis in mouse skin can be divided into the processes of initiation, promotion, and progression. The free-radical generator benzoyl peroxide is moderately active during the promotion stage. Repetitive treatment of mouse benign skin tumors (papillomas) with benzoyl peroxide (20 mg, twice weekly) increased the number of cumulative carcinomas per group by 325% and the number of keratoacanthomas by 44% compared to tumor-bearing Sencar mice treated with the promoter 12-O-tetradecanoylphorbol-13-acetate. The lack of increase in the number of cumulative papillomas per group due to benzoyl peroxide treatment suggests that benzoyl peroxide enhanced the progression of preexisting papillomas. The ability of benzoyl peroxide to enhance the progression of benign tumors to cancer should be considered when determining the human risk from exposure to this widely used chemical agent; in addition, biological assays specifically testing malignant progression may be essential and beneficial for determining an agent's carcinogenic risk.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1985

Night radiology.

Night radiology is the practice of the in-hospital radiologist from 4:00 to 11:00 p.m. His duty is to keep the interpretation of radiographs current. At the medical center described, an average of 95 radiographic examinations per day are performed during the evening and at night; 60 of these require immediate interpretation. Night radiology was instituted because of the large number of unmonitored and uninterpreted films that had to be dealt with the following morning. The night radiology duty is seven consecutive nights and is rotated among all nine staff radiologists. Night radiology provides a service that the emergency department and the private physician can rely on and can use without hesitation, delay, or resistance.

Hospital Departments↗

PubMed1982

Computed tomography of herniated and extruded nucleus pulposus.

Computed tomography (CT) is an accurate method of diagnosing herniated nucleus pulposus (HNP) in patients with back pain and radiculopathy. We evaluated 188 patients with 244 disk space explorations for the treatment of back pain and radiculopathy. In predicting HNP, CT was 92% accurate and myelography was 88% accurate. The only significant difference between the two modalities is at L5-S1. Here CT was 92% accurate in predicting HNP and myelography was 70% accurate, a difference that is statistically significant (p less than 0.01). The dural sac separation reduces the myelogram accuracy at L5-S1. In detailed evaluation of 188 patients with both CT-diagnosed and surgically confirmed HNPs, these HNPs were classified by location, calcification, size, and extrusion. If the maximum anteroposterior diameter of the HNP was less than one-half the anticipated normal sagittal diameter of the dural sac, the incidence of extrusion was less than 10%. If it occupied one-half or more of the anticipated normal sagittal diameter of the dural sac, the incidence of extrusion was greater than 90%. This difference is highly statistically significant (p less than 0.001). Thirty-five percent of the HNPs exhibited some degree of migration with the cephalic direction more common than the caudal direction. Computed tomography and myelography are both satisfactory methods of diagnosing HNP. The noninvasive CT gives direct anatomical information and is more accurate at L5-S1. If the physical examination correlates with the CT examination, then myelography may be bypassed and the patient treated with a high degree of confidence.

False Negative Reactions↗

PubMedDate not supplied

Lateral L3/4 herniated nucleus pulposus: clinical and imaging considerations.

This report examines 18 surgically proven L3/4 herniated nucleus pulposus (HNP), all having myelogram, CT and adequate neurological evaluation. It will focus on four cases where the herniation involved the neural canal (intervertebral canal). Comparison to the 14 spinal canal central herniations will be made. The clinical findings for lateral L3/4 HNP allowed a preimaging diagnosis to be made in three of the four cases. In the central group the correct preimaging diagnosis was made one of the 14 cases (P less than 0.01). There are numerous reasons why the central L3/4 HNP preimaging diagnosis is inaccurate as well as difficult to establish and these reasons are discussed in detail. The myelographic and CT findings of the lateral L3/4 HNP are clearly elaborated. All herniations were extruded. They poorly responded to conservative management. The duration of illness, onset of pain to surgical disk removal, for the lateral herniations was 34.8 days and, 154.4 days for the central group (P less than 0.05). The myelogram is a disappointing test in the diagnosis of lateral L3/4 HNP, but highly accurate in spinal canal L3/4 HNP. CT is a preferred imaging test being virtually positive in all cases.

Adult↗