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Biomedical subjects

H F Martin

Publications and source records attributed to H F Martin.

At least 19 recordsLinked to original sources
PubMed1994

Isopropyl alcohol intoxication in a neonate through chronic dermal exposure: a complication of a culturally-based umbilical care practice.

A 21-day-old boy presented to our emergency department hypotonic, lethargic, and intermittently unresponsive to pain. A workup for ketoacidosis, sepsis, and central nervous system hemorrhage was negative. A urine drug screen collected eight hours after hospitalization showed 39 mg/dl of isopropyl alcohol and 76 mg/dl of acetone. The first serum drug analysis was not performed until 18 hours after admission, at a time when there had been clinical improvement. The isopropyl alcohol concentration was 8 mg/dl, and the acetone concentration was 203 mg/dl. Management was supportive, and the patient stabilized. He was discharged from the hospital in good health in three days. A further review of the history showed no evidence for an oral exposure to isopropyl alcohol. However, since leaving the maternity hospital the mother had been applying gauze pads or cotton balls soaked with isopropyl alcohol to the umbilicus with every diaper change. We conclude that the child suffered from an isopropyl alcohol intoxication that occurred by absorption through the umbilical area.

1-Propanol↗
PubMed1992

The beneficial effects of a thromboxane receptor antagonist on spinal cord perfusion following experimental cord injury.

The eicosanoids thromboxane A2 and prostacyclin have opposing actions causing vasoconstriction and vasodilation respectively. The ratio of these two eicosanoids is thus an important determinant of circulatory homeostasis. An increase in this ratio occurs in certain inflammatory conditions with dramatic consequences in organ perfusion. In spinal cord trauma, in addition to direct physical perturbation of the spinal cord, it is likely that further structural and functional loss occurs as a result of decreased tissue perfusion precipitated by an increase in the thromboxane/prostacyclin ratio. This study evaluated hemodynamics and organ perfusion, 3 h following 24 g-cm spinal cord trauma in the rat. The role of thromboxane was investigated with an inhibitor of thromboxane synthesis (Dazoxiben) and with a receptor antagonist (13-APT). Cardiac output and blood pressure were unaffected by Dazoxiben, 13-APT, or spinal cord trauma. Injury effected approximately a 40% decrease in spinal cord perfusion from 0.41 to 0.25 ml/min/g which was not improved by the thromboxane synthase inhibitor, Dazoxiben. 13-ATP completely abrogated the decline in spinal cord blood flow flowing injury. Perfusion of other selected organs demonstrated little change as a result of the spinal trauma. Brain flow remained constant at 0.78 ml/min/g brain. Coronary blood flow, however, declined from 3.2 to 2.0 ml/min/g heart tissue. The data suggest consideration of the importance of thromboxane in therapeutic attempts to reduce secondary injury arising in spinal cord trauma.

Animals↗
PubMed1989

A method to measure the degree of control per se in the oral glucose tolerance test.

Using the glucose and insulin values from a 5-hr oral glucose tolerance test, nine quantitative measures have been developed to separate normal, "flat-curve," and non-insulin-dependent diabetic (NIDD) patients. The purpose of these measures is to quantify per se the degree of control operating in glucose homeostasis. A control index which is based upon Swan's minimizing principle and uses only the glucose values was successful in assessing the degree of control operating in glucose homeostasis.

Adult↗
PubMed1988

Temporal profile of thromboxane-prostacyclin imbalance in experimental spinal cord injury.

Thromboxane-prostacyclin imbalance may be an important determinant of platelet-vessel wall interactions that are vital in circulatory homeostasis. In experimental spinal cord injury, the vascular damage contributes substantially to the process of progressive secondary injury culminating in post-traumatic myelopathy. In this study, we found a time-dependent alteration of thromboxane-prostacyclin balance in the injured spinal cord with thromboxane dominance during the first 2 h: a time when maximal vascular injury is reflected by extravasation of 125I-labelled serum albumin. The thromboxane-prostacyclin imbalance reverted to favor prostacyclin by 18 h post-injury. This time-dependent alteration of thromboxane-prostacyclin balance should be considered in the planning of therapeutic attempts to prevent secondary injury by pharmacological modulation of platelet-vessel wall interaction.

6-Ketoprostaglandin F1 alpha↗
PubMed1988

A comparative study of serum ultrafiltrable, ionized, and total calcium in the diagnosis of primary hyperparathyroidism in patients with intermittent or no elevation in total calcium.

Measurement of serum ionized calcium has been shown to be more sensitive a method of diagnosing primary hyperparathyroidism than total calcium in patients with subtle or intermittent elevations of total calcium. The measurement of ionized calcium, however, is technically difficult. The measurement of serum ultrafiltrable calcium would circumvent technical difficulties because atomic absorption spectroscopy would be used to measure the calcium of a filtrate produced by passing serum through a filter which excludes protein-complexed calcium (Worthington ultrafree filter). The normal range for ultrafiltrable calcium (4.7 to 6.8 mg/dl) was determined in 138 patients by nonlinear least-squares analysis and chart review. The serum concentration of ultrafiltrable calcium correlated well with ionized calcium (r = 0.91). Previous studies have demonstrated no benefit in measuring ionized calcium, as opposed to total calcium, in the diagnosis of primary hyperparathyroidism unless there was subtle, intermittent, or no elevation of the total calcium. This comparative study of ultrafiltrable, ionized, and total calcium was, therefore, done in six patients with primary hyperparathyroidism who exhibited intermittent, minimal, or no elevations in serum total calcium. All six patients had symptoms referrable to hyperparathyroidism. All six underwent parathyroid surgery, and a parathyroid adenoma was found in each case. These six patients had a total of 24 concurrent preoperative determinations of ionized, ultrafiltrable, and total calcium levels. The total calcium value was elevated in only 9 of these 24 determinations (38%), ultrafiltrable calcium was elevated in 15 (63%), and ionized calcium was elevated in 23 (96%). The values of ionized calcium were elevated more frequently than both total calcium (p less than 0.0005) and ultrafiltrable calcium (p less than 0.025). The values for ultrafiltrable calcium were more frequently elevated than those for total calcium; this difference, however, was not significant. This study confirms our previous reports showing that ionized calcium is a more sensitive indicator of primary hyperparathyroidism in patients with intermittent or borderline elevation of the total calcium and extends those observations to show that ionized calcium is also a more sensitive indicator of primary hyperparathyroidism than ultrafiltrable calcium in this group of patients.

Calcium↗
PubMed1986

Pharmacokinetics and toxicity of frequent intermediate dose methotrexate infusions.

Serum methotrexate (MTX) levels were measured in 12 children (ages 2-18 years) who received a total of 56 24-h infusions of intermediate-dose methotrexate (500 mg/m2) at 1- to 3-week intervals. Mean peak serum MTX concentration 1/2 h following a bolus of 167 mg/m2 MTX (1/3 total dose) was 25.9 X 10(-6) M, mean plateau serum MTX concentration was 7 X 10(-6) M (over 8-24 h), and mean MTX clearance was 74 ml/min/m2. No significant changes in these values were noted with increasing number of infusions, suggesting that no metabolic adaptation occurred in the manner in which the body handled the MTX when it was given repeatedly in this fashion. However, adolescent patients (greater than or equal to 15 years) demonstrated a trend toward increased MTX clearance and decreased serum MTX concentration with greater than or equal to 5 infusions. In general, toxicity was minimal and did not increase with an increasing number of infusions. Significant toxicity was found only in adolescent patients, in spite of no documented difference in either MTX serum concentrations or clearance rates between adolescent and preadolescent patients.

Adolescent↗
PubMed1985

Prospective hematologic evaluation of gastric exclusion surgery for morbid obesity.

To evaluate the long-term frequency and severity of anemia and selected vitamin and mineral deficiencies after gastric exclusion surgery for morbid obesity, the authors prospectively examined hematologic and nutritional parameters in 150 consecutive patients. These patients underwent a standardized gastric exclusion procedure during a six-year period (1976-1982) and were closely followed for up to seven years (mean, 33.2 months). Anemia developed in 36.8% of the population at a mean time from operation of 20 months. It was more frequent in women than in men (p less than 0.01), and it required transfusions in 3.5% of the population. A low serum iron concentration developed in 48.6%, iron deficiency in 47.2%, a low serum vitamin B12 concentration in 70.1%, vitamin B12 deficiency in 39.6%, and RBC folate deficiency in 18% of the population. Both iron and folate deficiencies responded to oral replacement. As a result of the high frequency and severity of anemia and nutritional deficiencies noted, all gastric exclusion patients should, as a minimum, be placed on oral multivitamin preparations containing iron, folate and vitamin B12. In addition, it is imperative that these patients be followed closely for the remainder of their lives with appropriate studies and replacement as necessary.

Adolescent↗
PubMed1985

The effect of phenytoin on testosterone metabolism in vitro.

We recently encountered a male newborn with ambiguous genitalia who had been exposed to the anticonvulsant phenytoin in utero. In an attempt to investigate a possible teratogenic connection between phenytoin exposure and genital anomalies, the effect of phenytoin on the conversion of testosterone to dihydrotestosterone by human skin slices was studied. Neonatal foreskins obtained at circumcision were incubated for two hours with testosterone-4-14C and various concentrations of phenytoin. The incubation mixture was then assayed for testosterone, dihydrotestosterone, androstanedione, androstenedione, androstanediol, and androsterone using thin-layer chromatography and liquid scintillation spectrometry. The amounts of testosterone metabolites formed with phenytoin added were compared to values obtained under control conditions without phenytoin. There was a significant decrease in the amounts of 5 alpha reduced metabolites formed with increasing amounts of phenytoin added. Implications for male phenotypic sexual differentiation of the fetus exposed to phenytoin in utero are discussed.

Adult↗
PubMed1984

A multivariate statistical method for the establishment of maximum allowable exposure to toxic materials in the workplace.

A model has been developed for setting standard limiting concentrations for toxic substances in the body fluid or tissues of industrial workers. The method is very flexible, and allows the use of either univariate or multivariate data, and of classification schemes which are either supervised, unsupervised, or partially supervised. An index of subclinical biological damage is derived which is used to determine an optimal limiting exposure level. The model is applied to the particular case of selecting a maximum allowable concentration of blood lead in workers in industrial settings where lead toxicity is a danger.

Analysis of Variance↗
PubMed1984

Prospective metabolic evaluation of 150 consecutive patients who underwent gastric exclusion.

The effect of weight loss produced by gastric exclusion on the metabolism of previously morbidly obese persons was examined. A standardized gastric exclusion procedure was performed in 150 morbidly obese patients during a 6 year period. These patients were followed for from 6 to 60 months (mean 27.8 months). The mean excess weight loss was 75 percent and was maintained from 2 to 5 years. A small but significant decrease was noted during the first 3 to 6 postoperative months in the parameters of protein metabolism examined. Although this may reflect mild depletion in protein stores, of greater importance was the demonstration that these parameters spontaneously corrected themselves by 12 months. Mild abnormalities in serum electrolyte concentrations were noted in the postoperative period. They appeared to be related to dehydration, were not clinically significant, and also resolved spontaneously. Clinically significant abnormalities in divalent ions were absent. Significant and sustained reductions in blood pressure, fasting glucose concentration, serum triglyceride values, and uric acid and hepatic enzyme concentrations were demonstrated in the entire population. A small and non-sustained decrease in cholesterol was seen. Hypertension was eliminated in 96 percent of the affected subpopulation, diabetes in 100 percent, gout in 100 percent, hyperlipidemia in 92 percent, and improved hepatic function was found in 95 percent. These changes should reduce the overall morbidity and mortality of the patient population in the future.

Adolescent↗
PubMed1984

Development of calcium reabsorption by the allantoic epithelium in chick embryos grown in shell-less culture.

The allantoic sac of the chick embryo functions as a primitive urinary bladder, storing and modifying the excretory fluid produced by the embryo. We have used chick embryos grown in shell-less culture to study the in situ handling of Ca2+ by the allantoic epithelium. Between Days 8 and 13 of incubation (38 degrees C, 5% CO2), the [Ca2+] of the allantoic sac fluid declines from about 1.5 mM to less than 0.3 mM, with most of this Ca2+ reabsorption occurring between Days 10 and 11. In 13-day-old embryos, the allantoic epithelium reabsorbs within 24 hr 85-92% of 45Ca2+ injected into the allantoic sac, while in 9-day-old embryos 45Ca2+ reabsorption is less than 40% by 24 hr. This is evidence for the developmental onset of a Ca2+ reabsorption process in the allantoic epithelium. The allantoic fluid Ca2+ is reabsorbed into the embryo's blood in which the serum [Ca2+] is about 1.5 mM. Also, electrical potential profiles reveal that the serosal (mesenchymal) side of the allantoic epithelium is 15-30 mV positive compared to the mucosal (luminal) side. Thus, by electrochemical criteria this reabsorption process appears to be active.

Absorption↗
PubMed1984

The role of ionized calcium in the diagnosis of subtle hypercalcemia in symptomatic primary hyperparathyroidism.

This report details our continued study of the role of ionized calcium (CAI) in the diagnosis of symptomatic primary hyperparathyroidism (HPT) in patients with persistently normal total serum calcium (CAT) or fluctuating normal total serum calcium levels with elevated CAT. A patient was considered to have fluctuating CAT values if at least 40% of the CAT values were within the normal range. Our previous study demonstrated that CAI provided no additional diagnostic benefit in patients with HPT who had persistently elevated CAT levels. This retrospective study adds 15 additional patients to the four previously reported patients whose workup for HPT included normal or fluctuating normal total serum calcium with elevated CAT values. Eighteen of these 19 patients had complications or symptoms referable to HPT. Nine of these patients had renal calculi. CAT was measured by atomic absorption spectroscopy and CAI was measured by a calcium-selective ion flow-through electrode. One hundred fifty-one concurrent preoperative measurements of CAT and CAI from these 19 patients were used for analysis. Overall, 46 (30.5%) of the CAT values were elevated, whereas 134 (88.7%) of the concurrent CAI values were elevated (P less than 0.001). In three of these 19 patients all preoperative CAT values were within normal limits, however, 20 of the 21 (95%) concurrent CAI values were elevated. In the remaining 16 patients the CAT values fluctuated between normal and elevated. In all of these patients, at least 40% of the preoperative CAT values were normal, and in 15 of these 16 patients at least 50% of the preoperative CAT values were within the normal range. In this fluctuating category there were 130 concurrent values of CAT and CAI. Only 46 of these 130 (35.4%) CAT values were elevated, whereas 114 of the 130 (87.7%) CAI values were elevated (P less than 0.001). All patients underwent parathyroid operation; 15 patients had a parathyroid adenoma and four had hyperplasia. The CAI and CAT values returned to normal in all patients subsequent to operation. These data indicate that the measurement of serum ionized calcium appears to play an important role in the identification of symptomatic HPT in patients who have normal or fluctuating normal total serum calcium with elevated CAT values.

Adenoma↗
PubMed1983

Complications and weight loss in 150 consecutive gastric exclusion patients. Critical review.

Results of extensive follow-up for weight loss and complications in 150 consecutive patients who underwent a standardized gastric exclusion procedure have been presented. A comparative review of the literature has also been presented. All patients were followed for up to 6 years (mean 27.8 months). Only one patient was lost to follow-up. Complications during this period occurred in 54.7 percent of our patients. These were mainly postsurgical biliary disease and ventral hernias. Our recent experience has suggested that the latter complications could have been prevented. The absence of pulmonary embolism, pneumonia, and stomal ulcer in our series, as well as the low incidence of perforations, thrombophlebitis, and stomal and pouch complications suggest that the occurrence of these complications can be minimized as well. Patients in this series lost an average of 75 percent of their excess weight, 38 percent of their original weight, and stabilized at 30 percent above their ideal body weight. Ninety percent of the weight loss occurred in the first 12 months. Eighty percent of the patients, however, continued to lose weight 18 months postoperatively and 40 percent lost weight up to 24 months postoperatively. Weight loss has been maintained from 2 to 5 years. In conclusion, analysis of available data has demonstrated that careful patient selection, attention to technical detail, and close follow-up are of paramount importance for providing successful results and minimizing complications in the morbidly obese population who undergo gastric exclusion surgery.

Adolescent↗
PubMed1983

Liquid chromatographic profile classification of acute and chronic leukemias.

Reversed-phase high performance liquid chromatography and multivariate discriminant analysis are used for the classification of acute and chronic leukemias. Plasma or serum profiles, mainly of nucleosides, bases, and aromatic amino acids, are segmented into specific retention time intervals. Peak areas in each retention time interval are summed such that the chromatographic profile can be represented as a pattern vector formed from the linear combination of peak areas. The preprocessing techniques of autoscaling and variance weighting minimized inadvertent weighting and reduced the contribution of nondescriptive data components in the development of the discriminant function. The acute lymphocytic leukemia plasma samples and controls were classified with 100% sensitivity and specificity. Chronic leukemia serum samples and controls were categorized with sensitivity and specificity values of 93.7 and 87.6%, respectively.

Acute Disease↗
PubMed1983

The effects of spinal cord injury on somatosensory evoked potentials produced by interactions between afferent pathways.

The purpose of the present study was to determine the utility of somatosensory evoked potentials (SEPs) produced by interaction between afferent pathways for spinal cord injury evaluation. Interaction was measured as alterations in SEP configuration compared to controls. Monkeys anesthetized with N2O were used. Stimulus intensities were sufficient to excite all nerve fibers. The conditioning stimulus (CS) was applied to the left peroneal nerve and test stimulus (TS) to the left radial nerve. CS-TS intervals were 100 msec in duration. SEPs were recorded from primary cortical receiving area for the forelimb. Different surgical lesions were made at spinal cord level T3-T4. Amplitudes of TS-produced-SEPs remained unchanged postlesion. CS-produced-SEPs were found to be dependent upon the integrity of anterolateral column pathways. Accentuated interaction was observed following dorsal column ablation. Interaction was slightly enhanced after left hemisection but diminished after right hemisection or central cord lesion. Interaction between spatially separate afferent inputs as measured by SEP alteration was determined to be a sensitive indicator of spinal cord injury.

Afferent Pathways↗
PubMed1983

Far-field potentials as a method of monitoring acute and chronic spinal cord injury.

Far-field potentials (FFPs) were studied in monkeys to determine the utility of such responses in evaluating acute and chronic spinal cord injury. Monkeys (Macaca fascicularis) were anesthetized with 70% N2O 30% O2, immobilized with pancuronium bromide, and maintained on a respirator. Spinal cord transections were made at level T3-T4 and included bilateral dorsal columns or anterolateral columns, right or left hemisection, or central cord lesions. Percutaneous stimulation of both posterior tibial nerves was performed at a frequency of 3 Hz using 3-4 mA for 0.3 msec duration. Potentials were recorded from chronically implanted epidural electrodes (right ear reference) through a 300-3,000 Hz band pass filter. Each far-field potential represents the average of 256 individual responses recorded for a duration of 25 msec before and after cord lesion for up to 8 weeks. Seven reproducible components in the far-field potential could be identified. Following dorsal column transection all components were reduced in amplitude. After anterolateral column transection only latencies were altered. Right or left hemisections caused both attenuation of component amplitudes and latency alteration. Central cord lesions resulted in no detectable amplitude or latency disturbances. Control records likewise showed no changes. No major alterations, following day 1 posttransection, were observed, attesting to the relative stability of far-field potentials over long periods of time. Far-field potentials therefore may be useful in monitoring spinal cord injury.

Animals↗