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Biomedical subjects

M L Thomas

Publications and source records attributed to M L Thomas.

342 records · Page 19Linked to original sources
PubMedDate not supplied

Effects of long-term vitamin D deficiency and response to vitamin D repletion in the mature and aging male and female rat.

This study investigated the sex- and age-related alterations in calcium homeostasis in 39- to 82-week-old rats raised from weaning on a vitamin D deficient (-D) diet. It was found that vitamin D deprivation decreased the life span of male, but not female, rats. Female -D animals exhibited a steady increase in serum calcium with age from 39 to 82 weeks, although circulating calcium of -D animals never reached normocalcemic levels. There was no attenuation of the secondary hyperparathyroidism. Serum calcium of -D males was significantly lower than that of age-matched females at all ages when sufficient males were alive to make the comparison. Serum parathyroid hormone levels were decreased in -D females when serum calcium was elevated to hypercalcemic levels by calcium injection. Similarly, administration of vitamin D3 or 1,25-dihydroxyvitamin D3 elevated serum calcium and depressed parathyroid hormone in 14- and 22-month-old -D females. These animals also exhibited increased intestinal calcium binding protein content. Administration of vitamin D3 or dihydroxyvitamin D3 repaired renal adenylate cyclase refractoriness to parathyroid hormone. The sex- and diet-related alterations in serum phosphorus that were found at earlier ages disappeared by 67 weeks of age. Serum calcitonin was elevated in mature and aging +D males and females and -D females relative to younger animals. In -D males, calcitonin levels were less markedly elevated. The results of this study indicate that there are several important sex differences related to the regulation of calcium homeostasis in mature and aging rats. In addition, it was found that mature (14 month) and old (22 month) chronically -D female rats were able to respond to repletion with dihydroxyvitamin D3 or vitamin D within 10 days.

Aging↗
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Developmental changes in duodenal calcium transport in female rats related to ovarian hormone status and growth rate.

Duodenal active calcium (Ca) transport is known to decrease with age in male rats. The present studies were undertaken to extend this observation to female rats, and to determine whether alterations in active Ca transport are related to sexual maturation in the female. Everted duodenal sacs from intact and ovariectomized (ovx) rats were used to measure duodenal active Ca transport. Female rats were raised from weaning, and Ca transport was measured at 2-week intervals until 12 weeks of age. Transport rates were found to be the highest from 4 to 6 weeks of age, and then to decline over the next 4-6 weeks. However, if females were ovx as weanlings, the age-related decline in Ca transport failed to occur. Ovariectomy of immature females also prevented the slowing of growth rate which normally accompanies sexual maturation in female rats. We therefore repeated the experiment, pair-feeding the ovx animal to intact controls to maintain normal growth rates. When growth was normalized in this manner, the Ca transport rate in ovx animals declined with age at the same rate as in intact animals. Since ovx of sexually mature rats has been reported to increase growth rate, we studied the relationship between duodenal Ca transport and growth rate in females ovx at 12 weeks of age and pair-fed to age-matched intact females. After 5 weeks, ovx was found to have resulted in an increase in both weight and duodenal active Ca transport relative to the intact animals. Ovariectomy did not alter circulating levels of 1,25-dihydroxyvitamin D.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
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Techniques of phlebography: a review.

Phlebographic techniques for ascending and descending phlebography, and varicography based on personal experience of over 15,000 examinations are described. The indications for their use and their interpretation are discussed.

Contrast Media↗
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Thoracoscopy as a nonpharmacotherapeutic research modification for limiting postoperative chest pain.

Diminished tissue injury and shortened clinical recovery are benefits of using an endoscopic approach for patients needing operative procedure. In the course of developing an experimental model requiring procurement of topographically precise lung biopsy specimens, we sought to apply thoracoscopy as a research alternative to thoracotomy. In addition, we investigated the influence of thoracoscopy on postprocedure recovery practices using rabbits divided into four treatment groups. Rabbit groups 1 and 2 underwent thoracoscopy and lung biopsy while maintained by one-lung anesthesia. Additionally, group 2 had ketoprofen and bupivacaine HCl analgesics injected for treatment during postprocedure recovery. These two groups were compared to control rabbits in groups 3 and 4, which underwent inhalant anesthesia without thoracoscopy. Control group 3 also received the injection analgesic combination. During recovery, rabbit behavior was systematically assessed for evidence of pain. No behavior considered indicative of pain needing intervention was observed regardless of treatment group. Limited changes in plasma corticosterone, catecholamines, and prostaglandin E2 levels measured during recovery were difficult to associate with any treatment. Unexpectedly, significantly different mean corticosterone and catecholamines levels were detected in rabbits given the injection analgesic combination in the absence of thoracoscopic procedure, as compared to other treatment groups. The results highlight the importance of awareness that analgesic drug administration has the potential to alter homeostasis and affect interpretation of some study findings by its own guise. Correlation of the mean pain study results with plasma biochemical data supports preferential use of thoracoscopy as a refinement for limiting postprocedural pain in research models.

Anesthesia, Inhalation↗
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Characterization of tumor-associated antigens on human oral squamous cell carcinomas using monoclonal antibody 3F8E3.

Tumor associated antigen (TAA) on oral squamous cell carcinoma (SCC) was characterized using the monoclonal antibody (MAb) 3F8E3. Flow cytometric analysis revealed a varying degree of reactivity of MAb 3F8E3 to TAA on oral tumor cells. Pretreatment of SCC cells with pronase and trypsin annulled the reactivity of MAb 3F8E3. Sodium metaperiodate (NaIO4) and neuraminidase marginally enhanced the binding of 3F8E3 on oral SCC cells. The studies indicate that the TAA recognized by MAb 3F8E3 on oral tumors is a protein moiety. On Western blotting MAb 3F8E3 showed reactivity to proteins with a molecular weight of 60-66 kDa on oral tumor lysates. MAb 3F8E3 reacted strongly to recombinant human hsp60 and 70 in ELISA. The results suggest that MAb 3F8E3 may react to an epitope expressed on a family of heat shock proteins.

Animals↗
PubMedDate not supplied

Improved techniques for lumbar aortography.

The use of a large volume technique (60-100 ml of contrast) for lumbar aortography is recommended for routine use in the investigation of peripheral arterial disease of the legs. With this method lesions are less likely to be missed and more information is obtained. Using the modern contrast media such as iothalamate, the complications due to contrast medium are not significantly greater than with the conventional volume technique. In Leriche syndrome, although the proximal end of the arterial occlusion can be demonstrated using conventional volume anortography, the distal end, and the arteries below the occlusion can usually only be shown by using a relatively large volume of contrast. Movement of a patient with a lumbar aortography needle in position is safe. Additional projections such as obliques to show the origins of the profunda femoris arteries or the arteries of the feet, can be taken if required. Complications due to stripping of the aortic wall are diminished if a blocked ended single side opening lumbar aortography needle is used.

Aortography↗
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The value of arteriography of the hand in the Raynaud's syndrome.

The hand arteriograms of 18 patients with Raynaud's syndrome are reviewed. In 17 of the patients the arteriographic abnormality consists of digital artery occlusions, collaterals and diminished vascularity of the tips of the affected fingers. These changes are non-specific and do not correlate with the clinically diagnosed underlying arterial disease. The results of upper thoracie sympathectomy are unrelated to the type or severity of the angiographic changes. It is suggested that hand arteriography has little place in the diagnosis or management of patients with Raynaud's phenomenon. Arteriography is only of value to demonstrate a proximal source of digital emboli.

Adolescent↗
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Intravenous digital subtraction angiography in the management of peripheral vascular disease.

All patients undergoing peripheral injection intravenous digital subtraction angiography (ivDSA) for peripheral vascular disease during 1987 have been reviewed (140 patients). The radiological distribution of disease was aorto-iliac occlusive (AI) 36 (23%), femoropopliteal (FP) 68 (44%), mixed AI/FP 36 (23%). Clinical diagnosis was correct for AI disease in 92%, for FP disease in 65% and for mixed AI/FP disease in 47%. ivDSA was the only investigation required for management in 111 of all 140 patients (79%), and in 33 of the 36 patients with AI disease (92%), but was less accurate in defining femoropopliteal disease, 22 patients (32%) requiring additional arteriography. Conventional arteriography was performed in 200 patients in 1982 compared with 100 in 1987. ivDSA is particularly suitable for the investigation of AI disease, a condition which is accurately detected by clinical examination, with a reduction in morbidity and bed occupancy.

Angiography, Digital Subtraction↗
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A modified technique of pre-operative aortography to demonstrate the complete arterial tree of the lower limb.

One hundred consecutive aortograms were studied to establish the efficacy of conventional arteriography in demonstrating distal vessels and the pedal arch. The standard technique was modified by using a long injection time, a large volume of contrast material (iopamidol 370), prolonged filming and multiple exposures of the feet. On the basis of these examinations each limb was classified as having aorto-iliac disease (18 limbs), superficial femoral disease (103 limbs), combined segment disease (28 limbs) or generalised disease (51 limbs). Calf and ankle arteries were seen in 196 of the 200 limbs (98%). Patency of the pedal arch was established in 184 (92%). Fourteen percent of the group of patients with combined segment disease did not have their pedal arch visualised and this group contained most of the examination failures. This modified method of aortography can demonstrate the entire arterial tree from the aorta to the foot in 92% of limbs with symptomatic chronic atherosclerotic disease. This allows the majority of peripheral vascular reconstructions to be planned and performed without the need for intra-operative arteriography.

Angiography↗
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Reasons to strip the long saphenous vein.

Whether the long saphenous vein (LSV) should be stripped or not remains contentious. Varicography in patients with recurrent varicose veins frequently demonstrates an intact LSV. A series of 41 varicograms have been reviewed to find how often an unstripped LSV is associated with recurrence. Thirty-two patients, 22 female and 10 male, of mean age 49 years (33-78 years) were investigated. Forty-one limbs had previously had high saphenous ligation, yet still had clinical and ultrasound evidence of superficial venous reflux from a source above the knee. The mean interval between first and the last operations was 16 years (2-33 years). An intact LSV in some part of the thigh was present in 22/41 limbs (54%). Midthigh perforator incompetence (MTPI) via the unstripped LSV was present in 14/41 limbs (34%) and MTPI direct from femoral vein to a superficial varix occurred in 6/41 limbs (15%). The commonest problem is a residual communication at the groin found at operation in 80 p. cent of limbs. Accurate saphenofemoral ligation is crucial but we suggest that recurrence from MTPI via the intact LSV, and the possibility of recanalisation from the upper end of the intact LSV to the femoral vein are arguments for continued stripping.

Adult↗
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The value of intravenous digital subtraction angiography (IV-DSA) in the pre-operative assessment of abdominal aortic aneurysms.

Twenty patients with abdominal aortic aneurysm were investigated by intravenous digital subtraction angiography (IV-DSA) and the usefulness of this technique as a pre-operative procedure is evaluated. All the patients had, in addition, either conventional aortography, computed tomography, ultrasound or a combination of all three and the results compared with the IV-DSA. It is suggested that IV-DSA is a useful and safe initial investigation for the pre-operative assessment of patients with abdominal aortic aneurysms.

Aged↗
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Differentiation of ruptured aortic aneurysm from acute expansion by computerised tomography.

CT scans were obtained in five patients who presented with abdominal pain and were found to have an abdominal aortic aneurysm without evidence of hypovolaemia. A periaortic haematoma and evidence of a rupture was found on scanning in three of the patients and confirmed at immediate operation. A retrospective diagnosis of rapidly expanding (acute) aneurysm was made in the other two patients in whom no other pathology was found at early elective operation. CT scanning is useful in differentiating small well-controlled ruptures from rapidly expanding aneurysms.

Acute Disease↗
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Descending phlebography: a comparison of three methods and an assessment of the normal range of deep vein reflux.

Twenty-three legs in 13 patients without evidence of deep vein disease have been examined by descending phlebography using 3 techniques: with the patient semi-erect with no Valsalva manoeuvre with the patient semi-erect with a controlled Valsalva manoeuvre and with the patient supine with a standard Valsalva manoeuvre. It is concluded that the examination performed with the patient supine, using a standard Valsalva manoeuvre, is the most convenient and easiest to interpret of the variation. It is also suggested that deep vein reflux up to Grade 2 is within the normal range.

Adult↗
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Agenesis of the iliac veins.

Three case reports of patients with the rare anomaly of agenesis of the iliac veins are presented. It is emphasised that full phlebographic investigation should be carried out in such patients before surgical treatment is considered. It is pointed out that surgical ablation may exacerbate the symptoms of leg swelling and varicose veins for which the patients seek advice.

Adult↗
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The importance of high lumbar aortography in the Leriche syndrome.

Three patients with Leriche syndrome in whom a conventional low puncture lumbar aortogram failed to demonstrate the causative lesions are described. The aortic obstruction in Leriche syndrome is not always at the lower end of the aorta and may be high in the lumbar aorta. The importance of a high (D12/L1) puncture in patients with suspected Leriche syndrome, so that the whole of the abdominal aorta is visualised, is emphasised.

Adult↗