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Biomedical subjects

D F Adams

Publications and source records attributed to D F Adams.

At least 73 records · Page 4Linked to original sources
PubMed1986

Nuclear magnetic resonance spectroscopy of rat ventricles following supravalvar aortic banding. A model of left ventricular hypertrophy.

Left ventricular hypertrophy produced by supravalvar aortic banding in infant rats was studied by proton magnetic resonance spectroscopy. Weight gain at 11 weeks of age in the 11 male Sprague-Dawley rats with aortic bands placed at three weeks was similar to that of the 14 controls. The left ventricle of banded rats hypertrophied, increasing the ratio of left ventricle plus septum to body weight (LV + S/BW) by more than 50% (P less than .00001). Right ventricular weight (RV/BW) increased slightly (P less than .03). T1 and T2 relaxation times of LV + S, RV, and thigh muscle (Th) from the banded and control rats were compared. The T2 value distinguished hypertrophied from control LV + S (P less than .003), but not between RV or Th from the two groups. For banded rats only, the T2 value distinguished each muscle type: LV + S from RV, LV + S from Th, and RV from Th (P less than .00001 for each). For control rats, cardiac muscle was distinguished from Th (P less than .00001), but LV + S and RV were similar. The T1 value did not distinguish either the banded from the control group or any of the muscle types. Percent water content was similar for all tissues. Any correlation between water content and T1 or T2 was inconsistent or weak.

Animals↗
PubMed1986

Bioceramic implants in surgical periodontal defects. A comparison study.

The healing response of two commercially available bioceramics, beta tricalcium phosphate (TCP) and hydroxylapatite (HA), was compared after implantation in surgically created defects in dogs. Three 18 to 24 month old female Labrador dogs were used. Under general anesthesia 3-wall defects were created on the canines and premolars. The roots were planed, and reference notches were placed to identify the alveolar crest and the apical extent of the defects. TCP or HA was placed in alternating canine defects. The premolars received no implants and served as controls. Plaque management was accomplished by biweekly brushing with 0.2% chlorhexidine. Following healing periods of 5, 12 and 16 weeks, the dogs were sacrificed and perfused with 10% formalin. Six-mu step serial sections were evaluated by light microscopy. Healing against the root planed surface varied from a long junctional epithelium to a connective tissue reattachment in new cementum. TCP particles were actively resorbed by giant cells and macrophages and were incorporated into new bone matrix. The HA particles were encapsulated by fibrous connective tissue and rarely seen in contact with repairing bone. Bone formation was slower around HA particles at all time periods. Some evidence of HA particle resorption was seen at each time period.

Alveolar Process↗
PubMed1986

Prediction of postoperative visual acuity in cataract patients using the Flying Corpuscle Viewer.

One hundred one cataract patients were tested preoperatively for macular function using the Flying Corpuscle Viewer, a portable blue field entoptic device which utilizes the slit lamp as a light source. Preoperative appreciation of the "Flying Leukocyte Corpuscles" (FLC) indicated a high probability of good postoperative visual acuity, while lack of appreciation of the blue field entoptic phenomenon preoperatively had no predictive value for postoperative visual acuity.

Adult↗
PubMed1985

Computed tomography of the hindfoot with rheumatoid arthritis.

We are performing direct, coronally oriented computed tomographic (CT) scans of the subtalar joint in patients with rheumatoid arthritis. To date, 16 examinations have been performed in 14 patients, 5 of whom were scheduled to undergo subtalar arthrodesis. Scans were 4-7-mm thick and spanned the length of the subtalar joint. CT scans depicted and localized subtalar abnormalities clearly and precisely. On CT scans, patients showed a characteristic constellation of abnormalities including: soft tissue swelling, cartilage space narrowing, bony erosions, and a pes planovalgus alignment abnormality (consisting of increased heel valgus angulation, and a tendency toward flattening of the sustentaculum tali, and medial and downward slippage of the talar head). The clarity of the CT images facilitated the surgeon's pre- and postoperative evaluation. In particular, it was easy to plan the correction of the valgus deformity, anticipate any special requirements for reinforcing the articular surfaces, and assess the results of surgery. We conclude that coronal CT scans clearly demonstrate abnormalities and help the surgeon evaluate the rheumatoid hindfoot.

Adult↗
PubMed1985

Nuclear magnetic resonance spectroscopy of rat ventricles following chronic hypoxia: a model of right ventricular hypertrophy.

Nuclear magnetic resonance spectroscopy was used to study the effect of chronic hypoxia on both right (RV) and left ventricular and septal (LV + S) muscle. Rats in the hypoxic group, kept in a hypobaric chamber at 1/2 atm pressure for 2 weeks, developed right, but not left, ventricular hypertrophy (p less than 0.001). Tissues were studied within 2.5 h of return to air. T1 and T2 relaxation times of RV, LV + S and thigh muscle (Th) from hypoxic and control rats were compared. The T2 value distinguished hypoxic from control RV (p less than 0.002), but not hypoxic from control LV + S or Th, indicating that the change in relaxation time reflects cellular hypertrophy, and not hypoxemia. For hypoxic rats only the T2 value distinguished each muscle type: RV from LV + S (p less than 0.009), RV from Th (p less than 0.001) and LV + S from Th (p less than 0001). The T1 value did not identify either the hypoxic or control group or the type of muscle. Percent water content was similar for all tissues. For hypoxic RV, T2 correlated with the percent water content (r = 0.89; p less than 0.01). The sensitivity of T2 to the cellular changes associated with hypoxic RV hypertrophy could provide a means of detecting right ventricular hypertrophy.

Animals↗
PubMed1985

Comparison of I-123 IMP cerebral uptake and MR spectroscopy following experimental carotid occlusion.

Both I-123 IMP scintigraphy and MRI have been suggested as sensitive detectors of changes shortly after acute cerebral infarction. We compared the uptake of N-isopropyl I-123 p-iodoamphetamine (IMP) and MR spectroscopy of the brain after internal carotid artery ligation. Thirteen gerbils were lightly anesthetized with ether. After neck dissection, an internal carotid artery was occluded. After 2.8 hours, 100 muCi I-123 IMP was injected intravenously into the 13 experimental animals plus three controls. Seven gerbils remained asymptomatic while six developed hemiparesis. At 3 hours after ligation, the animals were killed. The brains were bisected and T1 and T2 relaxation times were determined for the right and left hemispheres by MR spectroscopy immediately after dissection. I-123 IMP uptake was then determined in the samples. Interhemispheric differences in uptake for I-123 IMP were 0.1 +/- 1.7% (SEM) in the control, 33.5 +/- 10% in the asymptomatic and 54.6 +/- 9.7% in the symptomatic animals. Significant differences were seen with I-123 IMP in 6/7 asymptomatic and 6/6 symptomatic animals. In conclusion, I-123 is more sensitive than T1 or T2 relaxation times for the detection of cerebral perfusion abnormalities. Prolongation in T1 and T2 relaxation times correlates closely with increased brain tissue water content and the development of symptoms, indicators of structural brain damage and probable infarction.

Amphetamines↗
PubMed1985

The detection of inflammation in collapsed lung by alterations in proton nuclear magnetic relaxation times.

The purpose of this study was to establish the proton NMR relaxation times of collapsed but otherwise normal lung tissue and to determine whether an inflammatory process within a collapsed lung can be detected by alterations in relaxation times. The lungs of three groups of rabbits were studied: group A (n = 7) had a sterile collapse of one lung for two days. The two other groups also had one lung collapsed, but with bacterial (group B, n = 6) or chemically induced (group C; n = 6) pneumonitis superimposed. The contralateral lung, which was acutely deflated at the time of thoracotomy, served as a control in each animal. T1, T2 and the total water content were measured on freshly excised lung samples. In group A, there was no significant difference in T1 (606 +/- 14* ms vs. 595 +/- 18 ms;* = SEM) or T2 (80.6 +/- 1.7 ms vs. 78.4 +/- 2.6 ms) between the collapsed and the control lung tissue. In each animal in groups B and C, T2 was longer in the collapsed lung with superimposed pneumonitis than in the control lung tissue (group B: 116.8 +/- 6.9 ms vs. 82.9 +/- 1.8 ms, P less than .001; group C: 120.5 +/- 5.9 ms vs. 86.0 +/- 1.5 ms, P less than .001). T1 changes were similar, but less marked. There was a linear relationship between the relaxation times and the total water content of the lung samples (T1:r = 0.87; T2:r = 0.91). It is concluded that proton NMR may have a potential in detecting disease such as inflammation in collapsed lung tissue based on differences in relaxation parameters compared with normal lung areas.

Animals↗
PubMed1985

The detection of cardiac allograft rejection by alterations in proton NMR relaxation times.

The ability of proton NMR relaxation times to detect cardiac allograft rejection was studied in an inbred rat heterotopic cardiac transplantation model. Hearts from 25 Lewis X Brown Norway F1 hybrid rats were anastomosed to the abdominal aorta and vena cava of Lewis recipients; 25 Lewis donor hearts served as isograft controls. Groups of five allografts and five isografts were harvested daily between two and six days post-transplant. The relaxation times T1 and T2 of the transplanted hearts were determined in vitro with a 10 MHz spectrometer. T1 and T2 values in allografts did not differ significantly from those in isografts at days 2 and 3 post-transplant. However, at days 4, 5, and 6 T1 and T2 of the allografts were significantly prolonged. This finding correlated with an elevation in tissue water content and the onset of rejection as determined histologically. An additional 21 allografts, treated with cyclosporine, were studied in the same way from four to more than 100 days post-transplant. T1 and T2 values of these treated allografts did not change significantly during the observation period and were similar to the relaxation values obtained in the isografts at days 2 to 6. These data suggest that serial measurements of myocardial T1 and T2 may be useful in detecting acute cardiac allograft rejection and monitoring the effect of antirejection treatment.

Animals↗
PubMed1985

Inhibitory effect of periodontally diseased root extracts on the growth of human gingival fibroblasts.

Cementum shavings obtained from periodontally diseased and nondiseased areas of 100 removed, single-rooted teeth were extracted with either pyrogen-free water (PFW) for 5 minutes, 1 M citric acid for 5 minutes or 45% phenol-PFW for 90 minutes at 65 degrees C. The extracts were membrane-filtered, dialyzed exhaustively versus PFW, lyophilized, weighed and then dissolved in complete growth medium. The phenol-water or citric acid extracts of cementum shavings from periodontally diseased roots were positive for endotoxin by the limulus lysate assay (LLA). Pyrogen-free water extracts of diseased or phenol-water extracts of nondiseased cementum shavings were negative, or only slightly positive, respectively, for endotoxin by LLA. Media containing the various extracts were added to logarithmically growing cultures of human gingival fibroblasts (HGF). Separate cultures of HGF were exposed to Escherichia coli endotoxin at concentrations of 50, 100, 250 and 500 micrograms/ml to determine the growth-inhibitory effects of a known endotoxin. Cell growth was analyzed by measuring the incorporation of tritiated thymidine into cells. Suppression of HGF growth from 30 to 49% by E. coli endotoxin was concentration-dependent and linear over the concentration range of endotoxin tested. Pyrogen-free water extracts of diseased (endotoxin negative) or phenol-water extracts of nondiseased cementum shavings (slightly endotoxin positive) did not effect HGF growth. However, citric acid or phenol-water extracts of diseased cementum shavings (highly endotoxin positive) significantly suppressed HGF growth 58% and 61%, respectively. These results indicate that citric acid is effective in removing cytotoxic substances, presumably endotoxin, from cementum shavings and suggest that citric acid treatment is effective clinically in detoxifying periodontally diseased root surfaces.

Cell Division↗
PubMed1985

Radiologist as consultant: direct contact between referring clinician and radiologist before CT examination.

The need for better direct communication between referring clinicians and radiologists has recently been emphasized. Responding to this need, a system was designed and implemented that used a radiologist as a consultant for scheduling body computed tomographic (CT) examinations. Under this system (in the "experimental" period), the referring clinician was required to consult with a body CT radiologist to schedule an examination in addition to completing a standard written radiology requisition. Before implementing this system (in the "control" period), only the written requisition was required. Ninety-five percent of referring clinicians were willing to cooperate with the new system. Benefits of the verbal consultation system included obtaining more clinical information (p less than 0.001) than was on the requisition alone (2.05 +/- 1.72 extra clinical data items), formulation of improved scanning protocols, a reduction in the number of post-CT diagnostic tests, and improved clinician-radiologist rapport. The costs of the system were mainly the nearly 5 min it took to schedule each case. It was concluded that a system that uses the radiologist as consultant and requires oral consultation between clinicians and radiologists can be implemented and has measurable benefits for patient care.

Economics, Medical↗
PubMed1984

Computed tomography of the hindfoot.

This investigation used computed tomography (CT) to study the normal anatomy of the hindfoot and to demonstrate abnormalities in patients with rheumatoid arthritis, pes planovalgus , old trauma, and soft-tissue masses. The hindfeet of 10 normal volunteers and 17 patients were scanned in the coronal and axial transverse planes. The articular surfaces of the tibia, talus, and calcaneus were assessed, as were the relationships of each bone to the others. Normal subjects had markedly symmetrical hindfeet . The "heel valgus angle" (relating the calcaneus to the tibia) was 5.2 +/- 1.6 degrees (mean +/- standard error of the mean). The "sustentacular angle" (indicating the angle of elevation of the sustentaculum tali at the midsubtalar joint) was 18.3 +/- 1.3 degrees. The "medial offset" of the talar head with respect to the calcaneus (measured at the anterior subtalar joint) averaged 5.2 +/- 1.8 mm. Patients with rheumatoid arthritis had erosions involving both sides of the subtalar joint, leading to talocalcaneal alignment abnormalities. In patients with pes planovalgus the heel valgus angle was greater and the elevation of sustentaculum tali lower in the foot that was most severely affected. Bony talocalcaneal fusions, fractures, and the erosions of pigmented villonodular synovitis were detected on CT. The pattern of postoperative bone healing after attempted subtalar fusion could be demonstrated. We conclude that CT is a useful tool for pre- and postoperative evaluation of the hindfoot.

Adult↗
PubMed1984

Wallerian degeneration demonstrated by magnetic resonance: spectroscopic measurements on peripheral nerve.

Wallerian degeneration of rat sciatic nerves was induced by nerve section. Fifteen days later the degenerated nerves were compared with the intact contralateral nerves from the same animal. Histological sections showed the changes typical of wallerian degeneration: axonal degeneration and secondary demyelination. The freshly dissected nerves were analyzed by magnetic resonance (MR) spectroscopy at 10 MHz, and the water content was determined by dehydration. In the degenerated nerves there was a marked prolongation of both T1 and T2 relaxation times, accompanied by an increase of water content. The results demonstrate the sensitivity of MR for detection of secondary demyelination and disintegration of nerve structures. These results suggest that it should be possible to detect wallerian degeneration in MR images; this will have an important impact on neuropathological diagnosis of central and peripheral nervous system lesions.

Animals↗
PubMed1984

Usefulness of liposomes carrying losefamate for CT opacification of liver and spleen.

Losefamate, a hepatobiliary contrast agent, was encapsulated into liposomes to increase its ability to opacify the liver and spleen on computed tomographic (CT) images. Multilamellar lipid vesicles (lecithin, cholesterol, and stearylamine, in 4:1:1 molar ratio) containing iosefamate in their aqueous phase were prepared. Seven dogs received intravenous injections of 100-300 mg I/kg in one of three forms: encapsulated, unencapsulated, or a mixture of the two in equal parts. Animals that received the opaque vesicles had marked opacification of their livers, bile ducts, gallbladders, spleens (maximum 106 H enhancement), and gastrointestinal tracts. Spleen CT values (an indicator of encapsulated material uptake) were always higher in these dogs than in the animals receiving equivalent amounts of unencapsulated iosefamate alone. At the high-dose level, liver uptake of the encapsulated materials was also greater. Liposome-encapsulated hepatobiliary contrast agents are effective liver and spleen opacifiers for CT imaging in the dog.

Animals↗
PubMed1983

A prospective study of computed tomography and ultrasound in the detection and staging of pelvic masses.

Findings from computed tomography (CT) and ultrasound (US) examinations of 74 patients who were clinically thought to have pelvic masses and of 110 patients who had possible recurrence of pelvic tumors were analyzed. There was no significant difference in the ability of the two modalities to identify masses or to predict disease extent. Although both CT and US failed to detect some examples of spread outside of the pelvis, overstaging (apart from two cases of unconfirmed parametrial spread) did not occur with CT and occurred only once with US. The sensitivity was 0.96 for CT and 0.91 for US in the detection of pelvic masses. Both modalities had an accuracy of 0.81 in the detection of recurrent disease.

Diatrizoate↗
PubMed1983

Computed tomography, ultrasound, and scintigraphy of the liver in patients with colon or breast carcinoma: a prospective comparison.

A prospective evaluation of computed tomography (CT), ultrasonography (US), and Tc-99m sulfur colloid scintigraphy of the liver was performed in 189 patients who had either colon (n = 129) or breast (n = 60) carcinoma. Imaging was performed with fourth-generation CT scanners, gray-scale or phased array ultrasound scanners, and 37-tube gamma cameras. Studies were evaluated independently and receiver operating characteristic (ROC) curves were constructed. In addition, a standard 2 X 2 matrix analysis was performed. In patients who had all three examinations (n = 122), the matrix analysis showed that CT had a slightly higher sensitivity (0.93) than scintigraphy (0.86) or US (0.82); specificities were 0.88, 0.83, and 0.85, respectively. These differences were not statistically significant. However, ROC curves showed that CT had the highest true-positive ratio at every false-positive ratio, and that US had the lowest. The performance of CT did not differ significantly from that of scintigraphy, but was better than that of US (p less than .05), especially in patients with breast carcinoma. Overall, CT provided the most accurate means for detecting liver metastases from both primary lesions.

Breast Neoplasms↗
PubMed1983

Optimal resources for examination of the heart and lungs: cardiac catheterization and radiographic facilities. Examination of the Chest and Cardiovascular System Study Group.

This is a revision of the 1976 report published under the auspices of the Inter-Society Commission for Heart Disease Resources. These guidelines provide a description of optimal resources, personnel, and working arrangements and should not be used to set minimal, standard, or uniform criteria or practices for all institutions. Included in the report are specifications for radiologic and physiologic equipment, description of case loads for maintaining safe and effective performance and considerations or complication rates. Also discussed are professional staff qualifications and relationships between physicians and technical and administrative services personnel. Other topics reviewed included laboratory location, electrical safety, and radiation protection as well as optimal facilities and equipment criteria for conventional x-rays. Newer imaging modalities are briefly considered, primarily to to emphasize that the field is rapidly changing. It is not possible, however to make specific recommendations concerning how these modalities will complement and/or replace more conventional techniques and approaches now considered appropriate and optimal.

American Heart Association↗