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Biomedical subjects

M Richardson

Publications and source records attributed to M Richardson.

At least 433 records · Page 24Linked to original sources
PubMedDate not supplied

Management of aggressive midface and orbital fibrous dysplasia.

OBJECTIVE: To discuss cosmetic and functional implications in the evaluation and treatment planning of large, aggressive midfacial fibrous dysplasias. PATIENTS AND METHODS: Eight patients (aged 2-38 years) with large fibrous dysplasias of the maxilla, zygomatic, and ethmoid bones requiring varying degrees of intervention and reconstruction were retrospectively reviewed. Patients with smaller lesions of these regions not requiring resection and reconstruction, as well those requiring sinus surgery alone were excluded from this review. RESULTS: All fibrous dysplasias in this review were monostotic, 6 originating in the maxilla, 1 in the zygoma, and 1 in the ethmoid. Five lesions (4 maxillary, 1 zygomatic) caused cosmetic deformity without functional deficits and required resection and/or contouring only with minimal reconstruction. The remaining lesions were invasive such that function of the eye and/or dentition was affected. These lesions were treated by aggressive resection and various degrees of reconstruction to optimize function. CONCLUSIONS: While fibrous dyplasia is classified as a benign process, local expansion can cause significant functional and aesthetic deformities. Each lesion should be thoroughly evaluated and, when vital structures are involved or threatened, total or subtotal resection should be considered. A variety of options should be available to the surgeon for definitive primary reconstruction.

Adolescent↗
PubMedDate not supplied

Fibrosarcoma of the infratemporal fossa in an 8-year-old girl.

The consultants agree that an open biopsy is generally necessary to establish the histology of a pediatric head and neck neoplasm. Although a frozen section may be useful to ascertain whether tumor tissue has been sampled, definitive therapy should be based only on the histopathologic interpretation of the permanent specimen. The consultants also agree that certain studies should be obtained prior to a biopsy. Dr. Grundfast recommends a chest x-ray, liver function tests, complete blood count, and an magnetic resonance scan. Dr. Healy would obtain additional CT cuts and an MRI scan. Dr. Richardson prefers coronal cuts on the CT scan and an MRI. The skull base is regarded as the area that might pose the greatest difficulty in obtaining a surgical margin. In addition, Dr. Healy states that eustachian tube involvement would compromise the resection. Although all consultants agree that the facial nerve should be sacrificed, they disagree as to how to reconstruct this defect. Dr. Grundfast would restore the mandibular profile with a prosthesis and reconstruct the soft tissue defect with a myocutaneous flap. Dr. Healy would use an iliac bone graft for the skull base defect and would replace soft tissue with a rectus free flap or a myocutaneous flap. Dr. Richardson favors a latissimus dorsi free flap. Because the survival rates for poorly differentiated fibrosarcomas of the head and neck are so low, the experts recommend adjunctive chemotherapy. Drs. Grundfast and Richardson would also advise radiotherapy. Dr. Healy feels that the morbidity of radiotherapy is too high and would use it only in cases of positive margins, parameningeal involvement, or perineural invasion.

Biopsy↗
PubMedDate not supplied

Purification and amino acid sequence of a highly insecticidal toxin from the venom of the brazilian spider Phoneutria nigriventer which inhibits NMDA-evoked currents in rat hippocampal neurones.

A new insecticidal toxin Tx4(5-5) was isolated from the fraction PhTx4 of the venom of the spider Phoneutria nigriventer by reverse phase high performance liquid chromatography (HPLC) and anion exchange HPLC. The complete amino acid sequence determined by automated Edman degradation showed that Tx4(5-5) is a single chain polypeptide composed of 47 amino acid residues, including 10 cysteines, with a calculated molecular mass of 5175 Da. Tx4(5-5) shows 64% of sequence identity with Tx4(6-1), another insecticidal toxin from the same venom. Tx4(5-5) was highly toxic to house fly (Musca domestica), cockroach (Periplaneta americana) and cricket (Acheta domesticus ), producing neurotoxic effects (knock-down, trembling with uncoordinated movements) at doses as low as 50 ng/g (house fly), 250 ng/g (cockroach) and 150 ng/g (cricket). In contrast, intracerebroventricular injections (30 microg) into mice induced no behavioural effects. Preliminary electrophysiological studies carried out on whole-cell voltage-clamped rat hippocampal neurones indicated that Tx4(5-5) (at 1 microM) reversibly inhibited the N-methyl-D-aspartate-subtype of ionotropic glutamate receptor, while having little or no effect on kainate-, alpha-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid- or gamma-aminobutyric acid-activated currents.

Amino Acid Sequence↗
PubMedDate not supplied

MR imaging of body fluid collections.

To evaluate the potential of magnetic resonance (MR) to characterize body fluids in vivo, we determined the relaxation times and the relative MR signal intensities of 42 body fluid collections in 42 patients. Twelve normal volunteers served as controls. We also studied albumin solutions at different concentrations and blood at various periods in vitro. Because of their long T1 relaxation times, most nonhemorrhagic fluid collections had low to intermediate intensity on images obtained with short repetition time (TR) and short echo time (TE) settings. Although the relaxation times and relative MR signal intensities of noninfected collections differed from those of infected collections, the values overlapped. On images obtained with short TR and short TE, blood in acute hemorrhages had intermediate signal intensity and serum in subacute hemorrhagic collections was the only pathologic fluid producing high signal intensity. Because of their relatively long T2 values, all the fluid collections were intense on images obtained with long TR and long TE settings; consequently, differences in intensity were less evident than on images obtained with short TR and short TE settings. Magnetic resonance allows reliable discrimination of subacute hemorrhagic collections from collections of other types, but the differentiation between acute hemorrhagic collections; nonhemorrhagic, noninfected collections; and nonhemorrhagic, infected collections is less accurate.

Adolescent↗
PubMedDate not supplied

Efficacy of surgical wound drainage in orthopaedic trauma patients: a randomized prospective trial.

OBJECTIVE: To study the efficacy of closed suction drainage in clean nonemergent surgical fracture fixation or bone grafting on the extremities or pelvis. DESIGN: A prospective randomized trial. SETTING: The orthopaedic trauma service of a Level I trauma hospital. PATIENTS: Patients were older than age eighteen years and undergoing clean nonemergent surgical fracture fixation or bone grafting procedures on the extremities (excluding hands and feet) or pelvis. INTERVENTION: The application of a surgical drain. MAIN OUTCOME MEASUREMENTS: Wound drainage, edema, hematoma and erythema, dehiscence, infection, and need for surgery or readmission were followed for six weeks. A univariate analysis with Student's t test for continuous variables and chi-squared analysis for all categorical data were used, with a p value of < or = 0.05 considered statistically significant. RESULTS: A total of 202 patients were randomized to 102 patients with no drain and 100 patients with a drain. There was no significant difference between the groups with regard to injury severity, systemic disease, age, body weight, physical status, or estimated blood loss. There was no significant difference between the drain and no-drain groups in any of the parameters evaluated. CONCLUSION: There is no significant difference between drained and nondrained wounds in clean, nonurgent orthopaedic trauma surgery. It appears that drainage systems can be safely eliminated in this group.

Adolescent↗