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Biomedical subjects

S D Cook

Publications and source records attributed to S D Cook.

At least 127 records · Page 7Linked to original sources
PubMed1992

Endophthalmitis at the Bristol Eye Hospital: an 11-year review of 47 patients.

We reviewed data from 47 patients who were treated for endophthalmitis at our hospital during the 11-year period 1980-90. The most common clinical features were hypopyon (75%), diminished vision (72%), ocular pain (68%), discharge (57%), corneal oedema (51%), conjunctival injection (49%), abnormal red reflex (34%), corneal ulcer (32%) and corneal perforation (6%). A total of 54 isolates were obtained from 41 (87%) of the 47 patients. Gram-positive bacteria were more common (72%), than Gram-negative organisms (22%). Two cases were due to fungi, and herpes simplex virus was isolated from one case. The two most common Gram-positive organisms were coagulase-negative staphylococci (25%), and Staphylococcus aureus (11%), while Pseudomonas aeruginosa predominated among the Gram-negative bacteria isolated (15%). Mixed bacterial species were obtained from 29% of the infected patients, including one from whom Vibrio fluvialis was isolated. Predisposing factors included ocular surgery (60%)--mostly for cataract extraction (47%), penetrating trauma (15%) and periocular (15%) or systemic (11%) infections. All patients received antibiotics (generally chloramphenicol and/or a beta-lactamase-stable penicillin plus an aminoglycoside) prior to culture, when treatment was adjusted according to specific aetiological agents. Seventy-nine per cent of patients received topical or systemic steroids. Vitrectomy (diagnostic and therapeutic) was performed on 21% of patients. Sixty-three per cent of culture-positive patients lost vision (no perception of light) in the affected eye, compared to 17% of culture-negative cases (P < 0.05 Fisher exact test). Similarly, a better visual outcome (acuity of 6/12 or better) was associated with coagulase-negative staphylococcal infection than with streptococcal or fungal infections.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Neurologic testing with somatosensory evoked potentials in idiopathic scoliosis.

A study was undertaken to determine if a somatosensory conduction delay is present in the posterior columns of adolescents with idiopathic scoliosis. Somatosensory evoked potentials were recorded after median and posterior tibial nerve stimulation in 12 adolescent subjects being followed for idiopathic scoliosis with an average age of 14.6 years (range, 12.0-16.6 years). Twelve normal controls matched for age, sex, race, and height underwent identical testing. Evoked potential peak latencies were measured and conduction velocities calculated. Results showed no difference between scoliotics and normal controls. Comparable posterior column conduction velocities were recorded in both groups. If a defect in posterior column function does exist in adolescent idiopathic scoliosis, as previously postulated, it is not reflected by a conduction delay as measured by somatosensory evoked potential testing.

Adolescent↗
PubMed1992

Intravenous gamma globulin in progressive MS.

In an attempt to prevent disease exacerbations, intravenous gamma globulin (500 mg to 2 g/kg) plus methylprednisolone was administered monthly to 14 patients with progressive multiple sclerosis, 11 of whom were steroid dependent. Seventeen exacerbations of disease activity were seen in 11 patients over a mean follow-up period of 7.8 months. Four exacerbations occurred in 3 patients within one month of receiving 1.6 to 2.0 g/kg of intravenous gamma globulin (IVGG). Most exacerbations occurred within 2 weeks of steroids being tapered; thus a steroid sparing effect of IVGG could not be demonstrated. We conclude that IVGG plus methylprednisolone can be given safely at monthly intervals for a prolonged period but in the dosage administered did not prevent exacerbations in 80% of patients with progressive multiple sclerosis.

Adult↗
PubMed1992

Broken intraocular lens during cataract surgery.

A case of planned routine extracapsular cataract extraction is described where surgery was complicated peroperatively by fracture of the posterior chamber lens implant. The technique of lens implantation is discussed.

Cataract Extraction↗
PubMed1992

Rate and types of fractures in corticosteroid-treated multiple sclerosis patients.

In a retrospective study of 103 corticosteroid-treated MS patients, the average rate of fracture events was 3.2% of the patients per year over 7.1 (+/- 5.7 SD) years at risk. Fractures of the ribs, pelvis, hip, or vertebrae occurred in 11 patients and became most common 5 years after starting steroids. Relatively high or low cumulative doses of steroids did not correlate predictably with the occurrence of fractures.

Adrenal Cortex Hormones↗
PubMed1992

Respiratory function in multiple sclerosis. Utility of clinical assessment of respiratory muscle function.

PURPOSE: The aim of this study was to assess the utility of clinical assessment of respiratory muscle weakness in MS. PATIENTS AND METHODS: We studied 40 MS patients who performed pulmonary function tests using standard procedures and measures of respiratory muscle strength. Descriptive clinical indices included a history of detailed neurologic findings, including upper and lower extremity weakness, cerebellar signs, and evidence of cerebral lesions and other clinical signs including dependence in activities of daily living, shortness of breath, weak voice, dysarthria and dysphagia. We devised an index comprised of four clinical signs: the patient's report of difficulty in clearing pulmonary secretions and his report of a weakened cough, the examiner's observation of the patient's cough, and ability to count on a single exhalation. RESULTS: Mean values of TLC (95 percent +/- 14) VC (91 percent +/- 19), and RV (106 percent +/- 34) were normal. By contrast, MVV (68 percent +/- 20), PImax (74 percent +/- 27) and PEmax (51 percent +/- 22) were decreased. Stepwise multiple regression indicated that the best single predictor of expiratory muscle weakness was the index score; the combination of index score, upper extremity weakness, and maximal voluntary ventilation accounted for 60 percent of the variance in PEmax. CONCLUSION: We conclude that clinical assessment is a better predictor of respiratory muscle weakness than spirometry and that a systematic clinical assessment supplemented by respiratory muscle assessment and MVV can uncover subtle respiratory muscle weakness in patients with MS.

Adult↗
PubMed1992

Torsional stability of HA-coated and grit-blasted titanium dental implants.

Hydroxylapatite (HA)-coated and grit-blasted (non-HA-coated) titanium dental implants were inserted into healed extraction sites of canine mandibles. After six weeks, the animals were killed and the implants mechanically tested in torsion to failure. Interface attachment strength, implant/tissue compatibility, integrity of the HA coating, and the location of interface failure were evaluated. Mechanical testing demonstrated an interface torsional strength of 3.98 +/- 0.93 MPa for the HA-coated implants and 2.25 +/- 0.65 MPa for the grit-blasted implants. This represents a 76.9% improvement in the maximum torsional interface strength, and is statistically-significant (p = 0.0004). On qualitative histologic analysis, interface failure was seen to occur primarily at the HA/implant interface, although failure through the HA coating and regions of bone/HA interface failure were observed. The HA-coated implants had bone in direct apposition to their surface with no fibrous tissue interposition. The grit-blasted implants also had regions of direct bone-implant apposition, but these areas were limited to a smaller proportion of the total interface area. There was no evidence of breakdown or change in thickness of the HA coating.

Animals↗
PubMed1992

A comparison of femoral and mandibular animal models for the evaluation of HA-coated implants.

The application of hydroxylapatite coatings promises marked improvement in the rapidity and durability of osseointegration for both dental and orthopedic metallic implants. Standard methods for the in vivo assessment of the performance of experimental implants include canine mandibular and femoral transcortical implantations. This study compared the results of the two procedures by use of similar HA-coated titanium implants. The results indicate that the rapidity of osseointegration and the maximum attachment strength for mandibular dental implants approximate those of the femoral transcortical implants, especially at longer post-operative intervals. We conclude that the two models are comparable for the purpose of evaluating the performance of this type of implant and can be used interchangeably by dental and orthopedic implant designers. HA-coating of titanium implants provides extensive osseointegration in both mandibular and long-bone models, with similar mechanical attachment strengths and histologic appearance.

Analysis of Variance↗
PubMed1992

The use of a new form of allograft bone in implantation or osseointegrated dental implants--a preliminary report.

The use of and early results with a new form of demineralized allograft bone tissue with the immediate placement of a dental implant are described. No occlusive membranes were utilized. GRAFTON Allogeneic Bone Matrix (ABM) is processed from human cortical bone into a thick gel consistency and packaged sterile in disposable syringes. The material was utilized in seven patients with seven implants. New bone formation was noted and, with the exception of two implants with a small amount of thread exposure, complete. It appears that treatment with the bone-grafting material produced clinical results similar to those reported with the use of barrier membranes and may provide an alternative to guided tissue regeneration. Further investigation appears warranted.

Bone Matrix↗
PubMed1992

Biocompatibility and biofunctionality of implanted materials.

The mechanical and chemical properties of metals, such as titanium, titanium-based alloys and cobalt-based alloys, and ceramics, such as Bioglass and calcium phosphate, make them suitable for implant applications. However, several factors affect the biologic response to these implanted materials. The predominant tissue found at the implant interface is affected by implant stability, material biocompatibility, and implant design and implant placement into the surgical site. Improvements in implant design and surface preparation may improve implant longevity and fixation for all implants materials.

Animals↗
PubMed1992

Hydroxyapatite-coated total hip replacement.

Biologic attachment of load-bearing orthopedic implants has developed as a response to long-term problems associated with polymethylmethacrylate cement fixation. Although early clinical results of uncemented hip and knee implants have been encouraging, histologic studies of retrieved implants have shown a distinct lack of bone apposition and ingrowth. Hydroxyapatite (HA) coatings applied to metallic implant substrates have been shown to enhance biologic fixation. These results have led to the clinical investigation of the use of HA-coated total hip replacements.

Durapatite↗
PubMed1992

Early clinical results with the hydroxyapatite-coated porous LSF Total Hip System.

The design of and early clinical results with the uncemented porous-coated LSF Anatomic and Midstem Total Hip Systems are described. In a Food and Drug Administration-approved program, a random selection method was used to determine which patients receive implants with a hydroxyapatite (HA) coating applied to the porous surface and which patients receive non-HA-coated implants. The early clinical results with the HA-coated systems appear superior to the non-HA-coated systems. A greater percentage of patients with HA systems have clinical scores in the excellent/good range, which is primarily a reflection of less prosthesis-related pain. Radiographically, all components appear well fixed with evidence of bone ingrowth. The HA-coated systems have a decreased incidence of radiolucencies, particularly in proximal zones.

Durapatite↗
PubMed1992

Tissue growth into porous-coated acetabular components in 42 patients. Effects of adjunct fixation.

Histologic examination was performed on 42 uncemented, porous-coated acetabular components removed for reasons not related to fixation. Included were 20 devices that had fixed pegs or spikes to aid in initial fixation and 22 devices that used screws through the component. The diagnoses and patient ages at insertion, times in situ, and reasons for removal were comparable for the two groups. Bone ingrowth was observed in 28 of the 42 acetabular components (67%). Of the 20 components with pegs or spikes, nine had no bone ingrowth, six had minimal bone ingrowth, four had moderate ingrowth, and one had extensive bone ingrowth. Of the 22 components with screws, five had no bone ingrowth, six had minimal bone ingrowth, six had moderate bone ingrowth, and five had extensive bone ingrowth. Two of the devices with screws also had external threads on the metallic shell; neither had any bone ingrowth, and the two accounted for two of the five devices having no bone ingrowth in this group. Bone ingrowth occurred more frequently, in greater amounts and was more evenly distributed anatomically in cups using screws for initial adjunct fixation. Roentgenographic and clinical findings were unreliable in predicting ingrowth of bone.

Acetabulum↗
PubMed1992

Results of implant retrieval from postmortem specimens in patients with well-functioning, long-term total hip replacement.

The evaluation of postmortem specimens provides a unique opportunity to gain understanding of the interface between host and well-functioning prostheses unavailable from revision specimens that, by nature, are accompanied by the artifacts generated during their removal. The preliminary findings from the relatively limited number of specimens described in this collaborative study demonstrate the value of the effort and are presented to encourage surgeons to participate in this program and to make their patients aware of the value of the information they may provide.

Adult↗
PubMed1991

Search for antibodies to neutral glycolipids in sera of patients with Guillain-Barré syndrome.

Sera from 54 patients with Guillain-Barré syndrome (GBS), 34 patients with other neurological diseases (OND) and 32 healthy controls were tested for antibodies to total lipid fractions and higher neutral glycolipid fractions isolated from human and dog nerves, purified Forssman glycolipid and a panel of purified neutral glycolipids by both an enzyme-linked immunosorbent assay (ELISA) and a thin-layer chromatogram (TLC)-overlay technique. IgM and IgG antibodies to total lipid fractions, as well as to galactocerebroside, ceramide dihexoside, ceramide trihexoside, and globoside were not significantly elevated in the sera of GBS patients as compared to controls. High levels of anti-asialo-GM1 IgG antibodies, however, were detected in 6 of 54 (11%) GBS patients and 1 of 30 (3%) OND patients. Intense reactivity with purified Forssman glycolipid and a number of glycolipid antigens in higher neutral glycolipid enriched fractions of human cauda equina and dog sciatic nerves was noted by TLC-immunostaining in many GBS and control sera. Although the levels of anti-Forssman IgM were significantly decreased in GBS sera compared with normal sera (P less than 0.05) and OND sera (P less than 0.02), the levels of anti-Forssman IgG antibodies were not significantly different. With the possible exception of IgG antibodies to asialo-GM1, our results suggest that serum antibodies against Forssman glycolipid and neutral glycolipids are not significantly elevated in GBS patients and, thus, are unlikely to play an important role in the pathogenesis of this disease.

Animals↗
PubMed1991

Antibodies to sulfated glycolipids in Guillain-Barré syndrome.

Sera from 53 patients with acute Guillain-Barré syndrome (GBS), 15 patients with chronic inflammatory demyelinating polyneuropathy (CIDP), 13 patients with other neurological diseases (OND) and 31 healthy controls were tested for IgM and IgG antibodies to sulfoglucuronyl paragloboside (SGPG) and sulfatide by both an ELISA and a thin-layer chromatogram-overlay technique. Although the mean levels of anti-SGPG or anti-sulfatide antibodies in GBS patients were not elevated compared to controls, the occurrence of anti-SGPG antibodies was more frequent in GBS patients than in controls (P less than 0.02). Acute GBS patients with antibodies to SGPG or sulfatide were clinically indistinguishable from other GBS patients. Our data suggest that elevated levels of antibodies to SGPG could be important in the pathogenesis of neuropathy in some GBS patients.

Animals↗
PubMed1991

Tissue growth into porous primary and revision femoral stems.

The authors studied 45 uncemented porous-coated femoral stems from 45 patients: 35 primary total hip arthroplasties and 10 revisions of either cemented (7) or uncemented (3) femoral components. Histologic sections were examined quantitatively for type, amount, and distribution of tissue ingrowth; these findings were correlated with clinical and radiographic data. Fibrous tissue ingrowth predominated in both groups. Of the primary arthroplasty group, the grade of bone ingrowth in 8 specimens was none, 14 minimal, 6 moderate, and 7 more extensive. In the revision cases, the grade of bone ingrowth in 5 was none, 3 minimal, and 2 moderate. Bone ingrowth was seen more frequently in the distal porous coating, particularly in the revision cases, and most often where direct stem-endosteal canal contact had occurred. While bone ingrowth can occur in uncemented revision stems, it generally appears less abundantly than in primary total hip arthroplasty.

Adult↗