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Biomedical subjects

R Lindsay

Publications and source records attributed to R Lindsay.

At least 109 records · Page 6Linked to original sources
PubMed1994

High-dose glucocorticoids in multiple sclerosis patients exert direct effects on the kidney and skeleton.

The effects of acute pharmacologic steroid treatment on skeletal and mineral metabolism were assessed in 56 multiple sclerosis patients who were to receive 1 g intravenous methylprednisolone for 10 days, followed by a 4 day intravenous and 28 day oral glucocorticoid taper. Serum and urine samples were obtained at baseline and then within 3 days, 1, 2, and 3 weeks after beginning steroids. A subset of patients (n = 11) had sampling throughout the 6 weeks of steroid administration and up to 8 weeks afterward. All mean basal biochemistries were normal except 25(OH)D, which was in the "insufficient" range (25-50 nM) at 10 nM. During and after steroid administration, there were no changes in ionized calcium, 25(OH)D, urinary hydroxyproline, or pyridinoline. There was an increase in 1,25(OH)2D and a decrease in serum phosphorus, accompanied by an increase in urinary phosphate clearance, within 3 days of administration (p < 0.006). Serum osteocalcin (BGP) decreased to below assay sensitivity limits within 3 days of steroid administration (p < 0.0002), increasing thereafter but remaining at 50% of baseline by the third week. PTH(1-84) increased to a peak at week 2 (p < 0.02), after both the 1,25(OH)2D peak and the serum phosphorus nadir. Tartrate-resistant acid phosphatase, urinary calcium, and urinary cyclic AMP all increased above baseline (p < 0.05) with a pattern similar to that of PTH. To investigate further the immediate effects of steroid administration, serum samples were obtained at the same four times on both the day before and the day after the first intravenous methylprednisolone dose in a randomly chosen subset of patients (n = 9).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1994

Determinants of bone mass in Chinese women aged 21-40 years. II. Pattern of dietary calcium intake and association with bone mineral density.

A study on the determinants of bone mass in young women is being carried out among 287 young Chinese women aged 21-40 years. The baseline cross-sectional data show that the mean dietary calcium intake, estimated from the quantitative food frequency method, was 448 mg/day (standard deviation = 219). About 50% of the calcium source was from vegetables and 22% from dairy products. Among women aged 21-30 years, those with a dietary calcium intake of at least 600 mg/day had a 4%-7% higher mean bone mineral density at the spine and femur when compared with those with a mean intake below 300 mg/day. In women aged 31-40 years, subjects belonging to the highest quartile of calcium density (> or = 35 mg/420 kJ) had a 3%-8% higher mean bone mineral density at the spine and femur when compared with those in the lowest quartile (< 20.8 mg/420 kJ). Favorable calcium intake is beneficial in this population of young women with habitual low dietary calcium intake.

Adult↗
PubMed1994

Bone mass measurement for premenopausal women.

Bone mass measurement is a useful tool in determining the risk of fracture. However, there are questions about whether or not bone mass measurement should be used in premenopausal women. Part of the problem concerns the issue of whether or not bone mass or bone density falls prior to menopause. Significant prospective data are still being gathered on this issue, which is hotly debated. In addition, even if there is a loss of bone density prior to menopause, it is not evident what clinical strategy would result from the measurement. At present, therefore, it seems prudent only to measure bone mass of women who have significantly impaired ovarian function or who are approaching menopause.

Absorptiometry, Photon↗
PubMed1994

Utah Growth Study: growth standards and the prevalence of growth hormone deficiency.

Serial measurements of elementary-school children were conducted for 2 consecutive years to assess height and growth velocity and to determine the prevalence of growth hormone deficiency (GHD) in American children. Trained volunteers measured 114,881 children the first year; 79,495 growth rates were calculated after the second measurements. The height and growth velocity curves generated were very similar to the currently used charts. We examined 555 children with short stature (< 3rd percentile) and poor growth rates (< 5 cm/yr). Five percent had an endocrine disorder. The presence of GHD (peak level, < 10 ng/dl with two provocative tests) was found in 16 previously unrecognized children; 17 children from this school population were already known to have GHD. Boys outnumbered girls 2.7:1 (p = 0.006). Six girls with Turner syndrome also were identified. We conclude that (1) the growth curves generated in the 1960s and 1970s are valid for children of the 1990s; (2) most children growing < 5 cm/yr (a commonly used threshold rate) will not have an endocrine disorder; (3) many children (48% in this study) with GHD and others with Turner syndrome may currently be unrecognized and untreated; (4) GHD appears to be more common in boys; and (5) the prevalence of GHD in the United States is at least 1:3480.

Child↗
PubMed1994

Behavioral self-regulation in adolescents with type I diabetes: negative affectivity and blood glucose symptom perception.

The hypothesis that negative affectivity (NA) is associated with accuracy of blood glucose (BG) symptom perceptions and diabetes control was assessed. After completing measures of BG symptom beliefs and NA-related constructs (i.e., attentional focus and trait anxiety), 35 adolescents with insulin-dependent diabetes monitored their physical symptoms and their actual BG levels 3 times daily for 2 weeks. Each subject's actual BG symptoms were determined by correlating symptom ratings with BG levels and were then compared with symptom beliefs. Those who were more internally focused were more able to discern which symptoms actually covaried with BG fluctuations; those with higher trait anxiety tended to misattribute non-diabetes-related symptoms to BG levels. Finally, interactions suggested that those who both attend to internal physical sensations and experience-heightened anxiety display poorer metabolic control.

Adolescent↗
PubMed1994

Effects of estrogen on response to edetic acid infusion in postmenopausal osteoporotic women.

We and others have hypothesized that estrogen helps preserve bone mass by affecting the PTH/vitamin D regulation of skeletal metabolism. To evaluate this theory, we tested the effect of estrogen administration on parathyroid sensitivity to hypocalcemic challenge. Subjects were postmenopausal osteoporotic women recruited from a tertiary care clinic (9 untreated and 12 receiving hormone replacement therapy at the time of the investigation). After baseline serum and urine testing, edetic acid (50 mg/kg) was infused over a 2-h period. Serum and urine samples were obtained over 5 h and 24 h after beginning the infusion. Serum ionized calcium dropped equally in both groups of women. There were overall group differences in PTH-(1-84) secretion (P < 0.02), with a greater peak (P < 0.04) and a longer period of elevation (P < 0.01) in the untreated than in the hormone-treated osteoporotic women. Serum 1,25-dihydroxyvitamin D [1,25-(OH)2D] and phosphorus as well as urinary phosphate and cAMP responded similarly in the two groups of women. Estrogenized osteoporotic women demonstrate a smaller PTH increment to hypocalcemia, indicating that the parathyroid has reduced sensitivity under the influence of estrogen. Despite the smaller PTH increase in estrogenized individuals, renal responses to PTH were the same as those in untreated osteoporotic women, implying an estrogen-mediated increase in the sensitivity of the kidney to PTH.

Administration, Oral↗
PubMed1994

High prevalence of vitamin D deficiency and reduced bone mass in multiple sclerosis.

BACKGROUND: Female patients with multiple sclerosis (MS) are at risk for osteoporosis because of gender, immobility, and corticosteroid use. METHODS: Bone mineral density (BMD) was measured by dual x-ray absorptiometry in 80 female MS patients admitted to a tertiary care hospital. All patients completed a questionnaire that included measurements of dietary intake and sunlight exposure. Biochemical indices of bone metabolism and turnover were measured in a random sample of 52 patients. RESULTS: BMD of the lumbar spine and femoral neck was 1 to 2 SDs lower in MS women compared with a healthy reference population. BMD was lower in patients with more severe MS. The mean 25(OH)D level of the sample population (43 nmol/l) was in the insufficient range, and 12 patients (23%) had frank vitamin D deficiency (< 25 nmol/l). BMD and age-related BMD (z scores) at all skeletal sites measured were lowest when 25(OH)D levels were deficient. Parathyroid hormone (PTH) was frankly elevated in 13% of patients. PTH levels were negatively correlated with 25(OH)D levels and with BMD. Dietary intake of vitamin D was below the recommended level in 80% of patients, and 40% reported no weekly sunlight exposure. After controlling for age, cumulative steroid use was not a determinant of BMD. CONCLUSIONS: BMD was significantly reduced in female MS patients, which might increase fracture risk two- to threefold. Vitamin D deficiency with secondary hyperparathyroidism is prevalent and is probably a significant cause of low BMD in this population. Vitamin D deficiency in the female MS patient might be safely and inexpensively corrected by the routine use of vitamin D supplements.

Adult↗
PubMed1993

Hormone replacement therapy for prevention and treatment of osteoporosis.

Estrogen therapy is clearly effective in the prevention and treatment of osteoporosis. Several estrogens and routes of administration are available. A progestin is required to protect the endometrium if the patient has a uterus. The duration of treatment required is unknown but probably is > or = 10 years for prevention and may be life-long, which is the requirement for patients with established disease. A regimen of patient monitoring can be easily established and must become routine for all patients on long-term treatment.

Administration, Cutaneous↗
PubMed1993

Estrogen protection against bone resorbing effects of parathyroid hormone infusion. Assessment by use of biochemical markers.

OBJECTIVE: Because parathyroid hormone (PTH) stimulates bone resorption, resistance to its actions might help maintain bone mass. We tested the hypothesis that the effects of estrogen on bone are accomplished in part by decreasing the sensitivity of the skeleton to the resorbing effects of PTH. STUDY DESIGN: Comparison of response to PTH infusion in untreated and estrogen-treated postmenopausal women with osteoporosis. INTERVENTION: (1-34) human PTH, 0.55 U/(kg.h), was infused intravenously over 20 hours. SETTING: The inpatient clinical research unit of a referral hospital. PATIENTS: Women with primary postmenopausal osteoporosis who were untreated (n = 15) or treated with estrogen (n = 17). MAIN OUTCOME MEASURES: Skeletal turnover indices including hydroxyproline, deoxypyridinoline, pyridinoline, tartrate-resistant acid phosphatase, alkaline phosphatase, bone Gla protein, and insulin-like growth factor-1. RESULTS: All basal indices were higher in untreated than in estrogen-treated women, but statistical differences were seen only for deoxypyridinoline and pyridinoline. During the 20-hour infusion, hydroxyproline/creatinine increased 0.023 mumol/mumol in untreated women but only 0.010 mumol/mumol in estrogen-treated women (P < 0.05). Corresponding changes for deoxypyridinoline/creatinine were 14.6 mumol/mumol and 3.5 mumol/mumol (P = 0.06). Tartrate-resistant acid phosphatase and pyridinoline increased only in untreated group. A circadian rhythm in circulating bone Gla protein was seen in both groups without clear PTH-induced effects or differences between groups. Alkaline phosphatase levels decreased and insulin-like growth factor-1 levels increased in both groups with no distinction between untreated and estrogen-treated women [corrected]. CONCLUSION: The estrogenized postmenopausal osteoporotic skeleton is less sensitive to the bone resorbing effects of acutely administered PTH. There are no differential effects on bone formation.

Aged↗
PubMed1993

Urinary hydroxypyridinium crosslinks of collagen as markers of bone resorption and estrogen efficacy in postmenopausal osteoporosis.

Estrogen deficiency-induced bone loss has been associated with accelerated bone turnover. Levels of some biochemical markers, such as serum osteocalcin (BGP), tartrate-resistant acid phosphatase (TRAP), and urinary hydroxyproline (OHP), have been shown to be related to the rate of bone turnover. They may therefore be useful in identifying the individual at risk for osteoporosis and monitoring the efficacy of the treatment. Two recently discovered markers, urinary pyridinoline (PYD) and deoxypyridinoline (DPD), are apparently directly related to bone matrix degradation and may be more accurate markers of bone resorption than OHP or TRAP. To evaluate the effects of menopause, osteoporosis, and estrogen replacement on the excretion of these new markers, we measured the levels of PYD and DPD and other biochemical markers of bone turnover in four groups of women, premenopausal healthy (PRE), postmenopausal healthy (POST), postmenopausal osteoporotic (UTO), and postmenopausal osteoporotic with estrogen treatment (ETO). Significant increases in PYD, DPD, BGP, TRAP, and OHP were found in POST and UTO groups compared with PRE. These increases were blunted by estrogen treatment when the levels of each of the markers returned to PRE levels. When comparing POST and UTO groups, significant increases were observed in UTO only for PYD, DPD, and urinary calcium but not for OHP, BGP, or TRAP. With subgroups matched for age and years from menopause, only DPD discriminated between POST and UTO. Indices of bone formation covaried with markers of bone resorption in the total population.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Phosphatase↗
PubMed1993

Criteria for successful estrogen therapy in osteoporosis.

Estrogens are well established as agents that stabilize the skeleton and reduce the risk of osteoporotic fractures among postmenopausal women. For maximum benefit, preventive therapy should begin as early as possible after ovarian failure begins to occur. Efforts to prevent bone loss are likely to achieve the best results when initiated prior to significant loss of bone tissue and trabecular penetration. An effect on skeletal bone mass can be obtained by any route of administration and transdermal estrogen use is an alternative to oral estrogen. Long-term therapy may reduce the risk of hip fracture by 50% and of vertebral fracture by a greater amount. The minimum effective dose is probably that which achieves circulating estrogen levels in the mid-follicular range. For women with a uterus in place, a progestin usually is provided to protect the endometrium; it is given cyclically in younger women but may be given continuously in women several years past menopause. Progestins do not interfere with the effects of estrogen on the skeleton, and it is possible that some progestins enhance the skeletal effects of estrogen. For patients with osteoporosis, estrogens can be used as first-line therapy since in these patients they have the same skeletal stabilizing effect and reduce the risk of recurrent fracture.

Bone Density↗
PubMed1993

Relationships between bone structure in the iliac crest and bone structure and strength in the lumbar spine.

The purpose of this study was to examine the relationship between histomorphometric variables of cancellous bone structure and ultimate compressive strength (UCS) in the second lumbar vertebra (L2) and to determine whether structural variables in the iliac crest are predictive of the same variables and of UCS in L2. At autopsy, 7.5 mm diameter cores were removed from the iliac crest and from L2 of 29 subjects who had died suddenly without bone disease. Cancellous bone volume (BV/TV, %) was significantly lower in L2 than in iliac crest due to lower trabecular number (Tb.N, per mm) and thickness (Tb.Th, microns). There were significant correlations between iliac crest and L2 for BV/TV, Tb.N and trabecular separation (Tb.Sp, microns), but not for Tb.Th. BV/TV was negatively correlated, and Tb.Sp was positively correlated with age at both sites. Tb.Th was not significantly correlated with age in the iliac crest, but a significant negative correlation was observed in L2. The UCS of vertebral cores was negatively correlated with age. BV/TV and Tb.Th in L2 were positively correlated with UCS in L2.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗