PubMed Health⌕ Search

Biomedical subjects

L Castillo

Publications and source records attributed to L Castillo.

At least 127 records · Page 7Linked to original sources
PubMed1990

[Neurologic diseases associated with the HTLV-1 virus in Panama].

Studies of the prevalence of the human T-cell lymphotropic virus (HTLV-1) in 1984 to 1986 in the Republic of Panama revealed a national seroprevalence of 1 to 2%. Since 1985 clinical epidemiological studies of neurological diseases associated to HTLV-1 are being done. Two hundred and fitly six clinical cases of thirty eight different neurological diseases of unknown etiology studied in the Neurology Services of the Santo Tomas Hospital and the Social Security Metropolitan Hospital Complex have been associated in some way to the HTLV-1. Twelve cases of progressive spastic paraparesis were identified and related to HLTV-1 as an etiologic agent. The ratio of men to women was maintained at 1:1 with the average age at onset at 44 years and without racial preference. There are important doubts about the association of this virus to multiple sclerosis. The seroprevalence of the HTLV-1 virus in Panama is found to be similar to that reported in neighboring countries and the association of tropical spastic paraparesis to THLV-1 infection is identified.

Adult↗
PubMed1988

[Hydatid cyst of the pancreas responsible for chronic recurrent pancreatitis].

Hydatid cyst of the pancreas is a rare localization of hydatidosis. It raises diagnostic problems which can only be solved by section of the surgical specimen. An exceptional case of hydatid cyst of the pancreatic tail which resulted in chronic recurrent pancreatitis, and a review of the literature, enable to put hydatidosis on the list of causes of pancreatitis.

Adult↗
PubMed1984

[Strategy for the formation of human resources in biomedical basic sciences].

The author describes the strategy followed in the Higher Institute of Medical Sciences of Havana for manpower training in basic biomedical sciences. This strategy is based on the Government's general policy for scientific development, and has resulted in the establishment of a network of centers of higher education and research institutes employing more than 3,800 professional and technical staff. Four-year specialization courses have been devised for physicians and dentists, and master's programs for which nonmedical professionals may apply. A system for the obtaining of scientific degrees has been structured together with an extensive program of graduate courses and training. The author comments on the excellent results obtained from the planned, efficient use of bilateral agreements with institutions in other countries and of the possibilities for training and qualification of specialists, the experience in which has already been offered to less developed countries.

Cuba↗
PubMed1979

Production of 1,25-dihydroxyvitamin D3 and formation of medullary bone in the egg-laying hen.

Renal 25-hydroxyvitamin D-1-hydroxylase, the percentage of medullary bone in the femur, plasma calcium, and plasma phosphorus were measured in female chickens reaching maturity. These parameters and plasma 1,25-dihydroxyvitamin D levels were also measured during the daily egg-laying cycle in mature hens. The renal 25-hydroxyvitamin D3-l-hydroxylase becomes elevated in maturing hens before and at the time of ovulation. This elevation in the 1-hydroxylase correlates with the elevation in total plasma calcium concentration but lags and at the time of ovulation and is followed by a further elevation of plasma 1,25-dihydroxyvitamin D levels. The plasma 1,25-dihydroxyvitamin D level remains high until 12 h postovulation. At this time, it falls to the preovulation level. No relationship could be found between the plasma 1,25-dihydroxyvitamin D levels and the changes in medullary bone found during the egg-laying cycle. However, plasma 1,25-dihydroxyvitamin D levels are highest immediately before and during the egg shell calcification phase of the egg-laying cycle.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1978

Synergistic effect of progesterone, testosterone, and estradiol in the stimulation of chick renal 25-hydroxyvitamin D3-1alpha-hydroxylase.

Castrate male chickens have low levels of renal 25-hydroxyvitamin D3-1 alpha-hydroxylase (13 pmol 1,25-dihydroxyvitamin D3/200 mg tissue . 10 min). This activity is markedly increased by the administration of 5 mg/kg estradiol and 5-20 mg/kg testosterone 24 h before in vitro measurement of the enzyme. Both hormones are required for this stimulation. The testosterone, but not estradiol, requirement for the stimulation can also be satisfied by progesterone. Progesterone (12.5 mg/kg) given in addition to estradiol and testosterone stimulates even further the 25-hydroxyvitamin D3-1 alpha-hydroxylase activity to very high levels (388 pmol 1,25-dihydroxyvitamin D3/200 MG tissue . 10 min). This is accompanied by a 3-fold increase in plasma 1,25-dihydroxyvitamin D3 (from 55 to 170 pg/ml), which provides in vivo evidence for the stimulation of the 1 alpha-hydroxylase by sex hormones in birds.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1977

The 24-hydroxylation of 1,25-dihydroxyvitamin D3.

The production of 1,24,25-trihydroxyvitamin D3 in vivo in vitamin D-deficient rats has been demonstrated from either 25-hydroxyvitamin D3 or 1,25-dihydroxyvitamin D3. The stereochemical configuration of the hydroxyl on the 24 position of 1,24,25-trihydroxyvitamin D3 has also been unambiguously established to be R. Nephrectomy failed to eliminate the conversion of 1,25-dihydroxyvitamin D3 to the 1,24,25-trihydroxyvitamin D3, establishing that the 24-hydroxylase can be demonstrated in at least one organ in addition to kidney in contrast to the 1-hydroxylase. 1,24,25-Trihydroxyvitamin D3 can also be produced in vivo from 1alpha-hydroxyvitamin D3 or from 24-hydroxyvitamin D3, analogs of vitamin D3 which are not naturally occurring. Using chick kidney mitochondrial preparations it has been demonstrated that the 24-hydroxylase is able to utilize 1,25-dihydroxyvitamin D3 as a substrate whereas it is unable to utilize 1alpha-hydroxyvitamin D3. In addition, the chicke kidney 1-hydroxylase is known to convert 24,25-dihydroxyvitamin D3 to the 1,24,25-trihydroxyvitamin D3, but this hydroxylase is unable to act on the 24-hydroxyvitamin D3. These results demonstrate that the renal vitamin D hydroxylases require that a hydroxyl be on the 25 carbon of the vitamin D molecule before it can be 1- or 24-hydroxylated.

Animals↗
PubMed1976

Control of renal vitamin D hydroxylases in birds by sex hormones.

Kidney homogenates from adult male Japanese quail or chickens demonstrate hydroxylase activity predominantly for the 24 rather than the 1 position of 25-hydroxyvitamin D3 (25-hydroxycholecalciferol). A single injection of 5 mg of estradiol-17beta into a male bird completely suppresses the 24-hydroxylase and greatly increases the 1-hydroxylase activity. Immature males do not respond well to estrogen alone, but they do respond well to estradiol plus testosterone. Testosterone alone has little or no effect on the hydroxylases of either species. Castrated male chickens show an estradiol response only when testosterone is also given. Optimal 24 hr responses to 5 mg of estradiol per kg in the castrate male were obtained with about 12 mg of testosterone per kg. These optimal amounts of estradiol and testosterone increased the activity of 25-hydroxyvitamin D3-1-hydroxylase approximately 225-fold (this enzyme is also known as 25-hydroxycholecalciferol 1-monooxygenase; 25-hydroxycholecalciferol, NADPH: oxygen oxidoreductase (hydroxylating), EC 1.14.13.13). These results demonstrate a strong regulation by the sex hormones of the renal vitamin D hydroxylases in birds.

25-Hydroxyvitamin D3 1-alpha-Hydroxylase↗
PubMed1975

The mobilization of bone mineral by 1,25-dihydroxyvitamin D3 in hypophosphatemic rats.

Administration of 1,25-dihydroxyvitamin D3 to thyroparathyroidectomized, hypophosphatemic rats on a low-phosphorus diet increases serum inorganic phosphorus and calcium concentrations. Experiments utilizing such rats treated with 45Ca and 32P ten days before use revealed that the rise in serum phosphorus in response in 1,25-dihydroxy-vitamin D3 is derived at least in part from bone mineral. This suggests that under conditions of hypophosphatemia, 1,25-dihydroxyvitamin D3 can mobilize bone in the absence of parathyroid hormone.

Animals↗
PubMedDate not supplied

Septic shock: pathogenesis and treatment.

Septic shock is the host's inflammatory response to infection. There are multiple endogenous mediators responsible for the pathogenesis of septic shock. Cytokines, nitric oxide and prostaglandins are some of the major mediators. The term sepsis syndrome allows for an earlier diagnosis and treatment. Management of septic shock is focused in maintaining hemodynamic stability and an adequate oxygen delivery and utilization. Careful attention to each organ-system is of paramount importance to prevent complications and improve outcome. Experimental therapies to modulate the inflammatory response are promising.

Acute-Phase Proteins↗