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Biomedical subjects

D R Shanklin

Publications and source records attributed to D R Shanklin.

At least 19 recordsLinked to original sources

Hepatic histopathologic condition does not correlate with laboratory abnormalities in HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet count)

OBJECTIVE: Our objective was to categorize the histologic findings in the liver in patients with HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet count) and to correlate these findings with the severity of clinical laboratory abnormalities. STUDY DESIGN: Eleven patients with laboratory criteria for HELLP syndrome who required cesarean delivery underwent needle biopsy of the liver under direct visualization. RESULTS: Eight patients had periportal hemorrhage, and six had fibrin deposition. Fatty infiltration was seen in four, one with large-droplet fat, three with microvesicular fat. There was no statistically significant correlation between the severity of the histologic findings of periportal hemorrhage and fibrin deposition and the clinical laboratory findings. Fatty infiltration did not correlate with the severity of the HELLP syndrome's histologic condition, but, in contrast, did correlate with thrombocytopenia and aminotransferase elevations. CONCLUSIONS: Laboratory abnormalities do not accurately reflect the severity of the underlying histopathologic condition in HELLP syndrome. We propose that all patients with HELLP syndrome, regardless of the degree of their laboratory abnormalities, be treated aggressively, primarily with delivery.

Adolescent

Polyethylene glycol superoxide dismutase and catalase attenuate increased blood-brain barrier permeability after ischemia in piglets.

BACKGROUND AND PURPOSE: Transport of urea across the blood-brain barrier is increased during postischemic cerebral reperfusion in the piglet. Ischemia/reperfusion also has been observed to increase apparent superoxide anion generation on the surface of the brain. The present study was designed to address the hypothesis that the increased transfer of urea into the brain after ischemia/reperfusion could be due to superoxide anion-induced alterations in blood-brain barrier permeability. METHODS: Blood-to-brain transfer of carbon-14-labeled urea was measured in four groups (n = 7 each) of newborn pigs: 1) control (no ischemia, no pretreatment), 2) pretreatment with polyethylene glycol superoxide dismutase (1,000 IU/kg) and polyethylene glycol catalase (10,000 IU/kg i.v.) but no ischemia, 3) no pretreatment and 20 minutes of ischemia followed by 2 hours of reperfusion, and 4) pretreatment with polyethylene glycol superoxide dismutase and polyethylene glycol catalase in addition to ischemia/reperfusion. The following brain regions were investigated: cerebrum, caudate, midbrain, pons, medulla, and cerebellum. RESULTS: Polyethylene glycol superoxide dismutase inhibited generation of superoxide anion by the brain during reperfusion after ischemia. Regional transfer of [14C]urea from blood to brain increased at 2 hours' reperfusion. This ischemia-induced increase in blood-to-brain transfer of [14C]urea was attenuated by pretreatment with polyethylene glycol superoxide dismutase and polyethylene glycol catalase: e.g., cerebrum Kin was 28 +/- 2 in the control group, 26 +/- 3 in the pretreated/no ischemia group, 67 +/- 5 in the untreated/ischemia group, and 40 +/- 2 ml.g-1.s-1.10(6) in the pretreated/ischemia group. After ischemia/reperfusion, cerebral blood flow was unchanged by pretreatment with polyethylene glycol superoxide dismutase and polyethylene glycol catalase. CONCLUSIONS: These data suggest that production of a partially reduced species of oxygen contributes to the increased urea transfer across the blood-brain barrier after ischemia in the newborn pig.

Animals

Isolation of skeletal muscle mitochondria from hamsters using an ionic medium containing ethylenediaminetetraacetic acid and nagarse.

An improved procedure is reported for the isolation of skeletal muscle mitochondria from hamsters and compared with our previous method. This procedure utilizes 20 mg% Nagarse in an ionic medium containing 100 mM sucrose, 10 mM EDTA, 100 mM Tris-HCl, 46 mM KCl, and 0.5% bovine serum albumin (BSA), at pH 7.4 (medium-B). Oxidative phosphorylation was studied by measuring ADP/O ratio and respiratory control ratio (RCR) using NAD(+)-linked pyruvate-malate (PM), as well as FAD-linked succinate (SUCC) as substrates. The mitochondria isolated in medium-B exhibited high RCR and high ADP phosphorylation capacity, and were superior to those prepared by our previous method. Electron micrographs of organelles isolated in medium-B revealed intact mitochondrial membrane and structural integrity, whereas those isolated with medium-A containing 50 mg% Nagarse depicted considerable damage including swelling, ruptured membrane, and loss of intramitochondrial matrix. Previously, we used a nonionic medium containing 210 mM mannitol, 70 mM sucrose, 0.1 mM EDTA, 10 mM Tris-HCl, 50 mg% Nagarse, and 0.5% BSA, at pH 7.4 (medium-A). Mitochondria isolated with medium-B yielded mean RCR values of 7.3 to 8.3 with PM, and values of 3.7 to 4.7 with SUCC as substrates, compared to 1.6 and 1.8 with PM, and 1.4 and 1.7 with SUCC for the organelles isolated using medium-A, respectively. Likewise, the ADP/O ratios were 2.6 to 2.7 with PM, and 1.6 to 1.7 with SUCC for medium-B preparations, compared to 1.5 and 1.8 with PM and 1.0 and 1.2 with SUCC for medium-A preparations, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals

Hypothyroidism reduces the rate of slow component A (SCa) axonal transport and the amount of transported tubulin in the hyt/hyt mouse optic nerve.

Thyroid hormone deficiency in the developing brain leads to disorders of neuronal process growth. This is evidenced by reduced axonal and dendritic size and complexity (Garza et al.: Developmental Brain Research 43:287-297, 1988; Ruiz-Marcos: Iodine and the Brain. New York: Plenum Press, pp 91-102, 1989). These findings may be related to alterations in the neuronal cytoskeleton in hypothyroidism, such as reduced or abnormal microtubular number and density (Faivre et al.: Developmental Brain Research 8: 21-30, 1983), and altered assembly, stabilization, and composition of microtubule protein in the hypothyroid brain. Neurofilaments also contribute to axonal caliber and process stability. Similar to microtubules, certain properties of neurofilaments are altered in developing hypothyroid axons (Marc and Rabie: International Journal of Developmental Neuroscience 3: 353-358, 1985; Faivre et al.: Developmental Brain Research 8:21-30, 1983) that may affect axonal caliber and process stability. Normal process growth is predicted on formation of appropriate numbers of microtubules and on the normal synthesis and axonal transport of cytoskeletal components [tubulin, microtubule associated proteins (MAPs), and neurofilament proteins]. Hypothyroidism might alter the neuronal cytoskeleton and neuronal growth either by affecting the developmental programs for expression of specific isoforms of cytoskeletal proteins or by changing the delivery of cytoskeletal proteins via slow axonal transport, particularly slow component a (SCa). Previous studies had demonstrated changes in the amount of specific microtubule protein isoforms and mRNAs (Stein et al.: Iodine and the Brain. New York: Plenum Press, pp 59-78, 1989a). To further elucidate the molecular basis for process growth abnormalities in the hypothyroid brain, we investigated slow axonal transport in the mouse to determine the effects of thyroid hormone deficiency on the rate and composition of SCa. Comparisons of SCa in the optic nerve of hyt/hyt hypothyroid mouse and euthyroid hyt/+ littermates and euthyroid progenitor strain, BALB/cBY +/+ mice, indicated that the velocity of SCa was significantly reduced in hyt/hyt optic nerve relative to hyt/+ and +/+. The axonal transport rate for tubulin, which is carried in SCa, was 0.118 mm/day in the hyt/hyt optic nerves. This rate was significantly different for the tubulin rates for the hyt/+ optic nerves (0.127 mm/day) and for the +/+ optic nerves (0.138 mm/day). Neurofilament proteins, as measured by the 140,000 daltons component, NFM, also appeared to be reduced in velocity in the hyt/hyt versus the hyt/+ and +/+ optic nerves.(ABSTRACT TRUNCATED AT 400 WORDS)

Actins

The site of the molecular defect in the thyroid gland of the hyt/hyt mouse: abnormalities in the TSH receptor-G protein complex.

The hyt/hyt mouse has a severe and pervasive primary inherited hypothyroidism with significantly depressed serum T4, elevated serum and pituitary TSH, and reduced thyroid gland iodide uptake. Previous ultrastructural and histologic analysis of the hyt/hyt thyroid gland along with these biochemical abnormalities support an inherited defect in TSH responsiveness of the hyt/hyt thyroid gland. In order to evaluate the potential site of the defect in the hyt/hyt mouse, we have studied the hyt/hyt gland and hyt/hyt TSH from a biochemical and molecular standpoint. Based on demonstrated bioactivity of hyt/hyt serum in the McKenzie bioassay, this reduced responsiveness to TSH in the hyt/hyt mouse is not due to reduced bioactivity of hyt/hyt TSH or a major structural abnormality in the hyt/hyt TSH molecule. In comparison to hyt/ + euthyroid littermates and +/+ BALB/cBY progenitor strain mice, the hyt/hyt mouse demonstrates a twofold reduction in thyroid gland basal cAMP and a markedly diminished response of adenylyl cyclase to exogenous TSH. However, hyt/hyt cAMP production is equivalent to the euthyroid mice after stimulation of thyroid glands by forskolin, cholera toxin, PGE1, and isoproterenol. These results support a defect in the TSH-G protein-adenylyl cyclase system in the hyt/hyt thyroid gland. Specifically, these findings suggest that the hyt/hyt mouse has a defect in TSH responsivity due to an inherited defect in the thyroid gland TSH receptor molecule. Since the hyt/hyt gland makes T3 and T4 but at diminished levels, the proposed defect in the TSH receptor would still impart partial function. Both hyt/hyt and euthyroid hyt/ + littermates make TSH receptor mRNAs of 5500 and 2400 base pairs. This suggests that the receptor defect does not represent a major structural abnormality of the gene. The receptor defect could represent a reduction in receptor number, receptor-TSH affinity, or TSH receptor-G protein coupling. The specificity of this effect on adenylyl cyclase-cAMP is shown by the reduction of TSH-cAMP regulated thyroid peroxidase (TPO) and thyroglobulin mRNAs in the hyt/hyt thyroid gland. Given the importance of TPO and thyroglobulin in normal thyroid hormone synthesis, the reductions in TPO and thyroglobulin mRNAs in the hyt/hyt thyroid gland may underlie the significant decrease in thyroid hormone production by the hyt/hyt mouse.

Adenylyl Cyclases

Ultrastructural aspects of preeclampsia. II. Mitochondrial changes.

Biopsy specimens were obtained under direct vision at the time of cesarean section from 47 patients (35 with preeclampsia and 12 normotensive patients) and from four women with cesarean section hysterectomies (all normotensive) as an extension of previous work. Tissues were obtained from the myometrium near the placental bed and from the opposite side of the uterus. Skin biopsies were also obtained from eight women with preeclampsia and liver biopsies were obtained from two patients with acute microvesicular fatty change of pregnancy (one with and one without concomitant preeclampsia). Specimens were examined histologically and by electron microscopy. Mitochondrial changes in small vessels, principally venules, in myometrial smooth muscle, myometrial interstitial cells, circulating leukocytes, epidermal and dermal cells, and hepatocytes were examined and compared between women with preeclamptic and normotensive pregnancies. These findings were then compared with mitochondria from 500 biopsies over the same 3-year interval to assess the possible role of delay in tissue fixation. There were 12 other biopsies from nonpregnant women of childbearing age. As further control on artifact, other specimens were initially sampled immediately in the operating room and then serially for up to 2 hours later. Artifact as a basis for the mitochondrial changes was ruled out by these procedures. Normal mitochondria undergo a morphologic conformational sequence with physiologic changes in substrate, oxygen consumption, adenosine diphosphate, and respiratory rate. The mitochondria of preeclamptic tissues show a central disruption that is outside this normal sequence or cycle. This disruption occurs more often and is more severe in preeclampsia than in normotensive pregnancies. In addition, the hypertrophic smooth muscle of the pregnant uterus has a complex of cytoplasmic organelles in a paranuclear location, usually apical, that contains a variable mixture of glycogen, the Golgi apparatus, endoplasmic reticulum, mitochondria, and small unidentified microvesicles. This complex has the location and appearance suggestive of a myometrial "power pack" of significance in metabolism and contraction. The presence of similar mitochondrial changes in a limited sample of nonuterine tissues is suggestive of a systemic metabolic disorder as an important feature of preeclampsia.

Cell Survival

Recurrent acute fatty liver of pregnancy.

The first reported case of recurrent acute fatty liver of pregnancy confirmed by biopsy is described. In this case a high index of suspicion led to an early diagnosis and intervention with resultant improved maternal and fetal outcome. Electron microscopic examination of a liver biopsy specimen proved more beneficial in confirmation of the diagnosis compared with routine microscopic examination.

Acute Disease

Effect of exogenous surfactant on the development of bronchopulmonary dysplasia in a baboon hyaline membrane disease model.

To test the effect of exogenous surfactant on the evolution of histopathologic changes of bronchopulmonary dysplasia (BPD), we conducted a study in a premature baboon hyaline membrane disease model. One hundred mg/kg bovine surfactant sonicated in saline or 3 ml/kg saline placebo was instilled via the trachea at about 10 min of age. The clinical status and physiologic changes were monitored for 9 days, and pulmonary histopathology was evaluated after death. Compared to the control, the surfactant-treated animals showed a significant improvement in arterial/alveolar oxygen ratio and pulmonary compliance, facilitating rapid weaning from assisted ventilation. Lung histology revealed that pulmonary parenchyma expanded 70% to 95% without features of early BPD. Dysplastic maturation, air trapping, or cellular atypia was not seen. In contrast, lung histology in the control group revealed alveolar expansion less than or equal to 50%, basal cell hyperplasia in the bronchial and bronchiolar epithelium, dysplastic maturation with cellular atypia, extensive epithelial erosion, and type II cell hyperplasia, all features of early BPD. The results of this study suggest that in the premature baboon model, exogenous surfactant therapy improves pulmonary functional abnormalities and lessens the histologic features of BPD, perhaps because of rapid weaning and reduced barotrauma.

Animals

Activated oxygen and arachidonate effects on newborn cerebral arterioles.

We have observed that pial arteriolar dilation in response to hypercapnia and hypotension is abolished after cerebral ischemia in newborn pigs. We determined whether direct generation of activated oxygen on the brain surface (OX: xanthine oxidase, hypoxanthine, FeCl3, and FeSO4) or topical arachidonate altered pial arteriolar responsiveness in a manner similarly to cerebral ischemia. OX, which generated more brain surface superoxide than reperfusion after ischemia, dilated pial arterioles. This dilation was reversed within 10 min of the end of exposure. OX produced ultrastructural changes in pial vessel endothelium and appeared to cause intravascular aggregation of granulocytes. After OX, prostanoid-dependent pial arteriolar dilations in response to hypercapnia and hypotension were attenuated, whereas constrictor responses to norepinephrine and acetylcholine and dilator responses to prostaglandin E2 and isoproterenol were not affected. After OX, hypercapnia increased cortical periarachnoid cerebrospinal fluid prostanoids modestly, whereas acetylcholine produced the normal strong stimulation of prostanoid synthesis. Arachidonate (10(-4) M and 7 x 10(-4) M) also caused reversible pial arteriolar dilation but did not alter subsequent pial arteriolar responses. Therefore, although arachidonate did not mimic the effects of ischemia-reperfusion on pial arteriolar reactivity, OX produced alterations that are qualitatively similar, although quantitatively less, than those produced by ischemia.

Animals

Dilation and evacuation for second-trimester genetic pregnancy termination.

Dilation and evacuation (D&E) is the most common procedure for second-trimester pregnancy termination currently used by United States obstetrician-gynecologists. Although this method carries morbidity and mortality rates significantly lower than methods requiring labor induction, the procedure most commonly used for second-trimester genetic terminations seems to be labor induction (eg, vaginal prostaglandin suppositories). Many geneticists appear reluctant to recommend D&E over induction methods of pregnancy termination because they perceive that fetal abnormalities cannot be consistently confirmed by evaluation of the products of conception obtained by D&E. We report here 60 consecutive patients who underwent D&E (14-22 weeks' gestation) after detection of fetal abnormalities. The prenatal diagnoses were confirmed in all cases. Our experience thus indicates that D&E is reliable in confirming most prenatal diagnoses and should be the procedure of choice when second-trimester pregnancy termination is chosen because of fetal abnormalities.

Abortion, Eugenic

Ultrastructural aspects of preeclampsia. I. Placental bed and uterine boundary vessels.

Biopsy specimens were obtained under direct vision at the time of cesarean section from 42 patients (33 preeclamptic and nine normotensive patients) and from three hysterectomies (all in normotensive patients). Mean gestational age was 32.8 +/- 0.9 week (range, 26 to 40 weeks) in women with preeclampsia and 36.1 +/- 1.1 weeks in normotensive women (range, 32 to 41 weeks). Tissues were obtained from the central placental bed and from nonplacental sites. Specimens were examined histologically and by electron microscopy. Ultrastructural changes in small vessels, primarily venules, were compared with preeclamptic blood pressure. Extensive ultrastructural endothelial injury was found consistently in both site and nonsite areas in all of the specimens from women with preeclampsia but not in normotensive women (p less than 0.0001). There was no apparent correlation between the type or degree of endothelial damage and maternal hypertension. The same types and relative severity of specific vascular injury were present in both placental and nonplacental sites. Endothelial and derivative vascular injury occurs more or less uniformly in the uterus in preeclampsia, especially along the boundary zone between maternal and fetal tissues.

Animals

Evaluation and characterization of the hypothyroid hyt/hyt mouse. I: Somatic and behavioral studies.

Mice homozygous for the autosomal-recessive gene hypothyroid (hyt) had congenital hypothyroidism of fetal onset after 15 days postconception. Neonatal hyt/hyt mice had reduced serum thyroxine ranging from 1/5 to 1/6 of normal as well as significantly delayed somatic and behavioral development. Delayed somatic development included retarded eye opening and ear raising, and reduced body length and body weight. The hyt/hyt animals compared to their normal littermates demonstrated delayed reflexive behavior and abnormal motor and adaptive behavior. The somatic and behavioral measures clearly distinguished hyt/hyt animals from their normal littermates even without T4 determination. The somatic and reflexive behavioral abnormalities in the hyt/hyt mouse were similar to other rodent models of human congenital hypothyroidism. The hyt/hyt mouse provided an ideal model for exploring the effect of severe primary inherited hypothyroidism related to deficient autonomous fetal thyroid function and was consistent with the hypothesis that thyroid hormone deficit in utero and in the early neonatal period significantly altered functional development.

Animals

Evaluation and characterization of the hyt/hyt hypothyroid mouse. II. Abnormalities of TSH and the thyroid gland.

The hyt/hyt mouse (BALB/cBY-hyt, C.hytRF) provides a useful model for exploring the effect of inherited severe primary hypothyroidism. Studies were undertaken to try to define the basis of the primary hypothyroidism in mice homozygous for the autosomal recessive gene, hyt. These mice had congenital hypothyroidism of fetal onset after 15 days post conception. Through their lifetime, the hyt/hyt mice had reduced serum thyroxine (T4), triiodothyronine (T3), reduced thyroid gland intralumenal colloid on electron microscopy and a 100-fold elevation of TSH-like activity compared to hyt/+ littermates. Thyroglobulin made in hyt/hyt animals was similar in size to normal thyroglobulin which was inconsistent with a major structural thyroglobulin gene defect. The thyroglobulin was iodinated. Marked, erratic dilation of rough endoplasmic reticulum (RER) was noted in hyt/hyt mouse follicular cells. Despite these ultrastructural findings, pulse chase and immunoprecipitation studies with isolated hyt/hyt and normal thyroid glands indicated that normal thyroglobulin processing occurred in the RER and Golgi of the hyt/hyt mice. The hyt/hyt thyroid glands were hypoplastic compared to hyt/+ littermates. Histologically, the hyt/hyt thyroid glands demonstrated an increase in smaller follicular cells, and greater variability in follicular size compared to hyt/+ littermates. Histological and ultrastructural abnormalities in the gland were similar to those seen in certain cases of human congenital hypothyroidism with TSH receptor insensitivity of the thyroid gland. These findings along with the significant TSH elevation, the reduction in colloid and in serum T3 and T4, the efficacy of the hypothalamo-pituitary-thyroid feedback system, and previous observations of reduced iodine uptake and intrathyroidal T4, suggested that primary hypothyroidism in the hyt/hyt mouse might be due to a defect in TSH responsivity of the thyroid gland.

Animals

The peripheral hypoechoic rim of the fetal heart.

The purpose of this study is to determine the origin of the hypoechoic rim around the fetal heart; this rim has been noted previously but there is disagreement as to its origin. Of 314 fetuses scanned, a four-chamber view was obtained in 290; a hypoechoic rim was present in 94% of these. In all cases in which a short-axis view could be obtained, the rim continued circumferentially through the ventricular septum. Because the rim continues through the septum, it cannot be pericardial fluid but is instead part of the myocardium. The presence as well as the origin of this normal hypoechoic rim around the fetal cardiac ventricles should be considered before diagnosing small pericardial effusions.

Diagnosis, Differential