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Biomedical subjects

L A Scott

Publications and source records attributed to L A Scott.

11 recordsLinked to original sources
PubMed1992

In vitro fertilization. Technology and methods.

The laboratory component of assisted reproductive technologies involves the manipulation and culture of male and female gametes in vitro, with the goal of producing viable embryos for transfer to a woman to enable the establishment of pregnancy. The biology of the gametes and resulting embryos dictates how they should be handled in vitro to maximize their potential at establishing a viable pregnancy. This article examines the biology of gametes and offers some suggestions as how best to proceed with the process of in vitro fertilization, embryo culture, and embryo transfer.

Acrosome↗
PubMed1991

Ligase-free subcloning: a versatile method to subclone polymerase chain reaction (PCR) products in a single day.

Often, it is convenient to subclone polymerase chain reaction (PCR) products into a plasmid vector for subsequent replication in bacteria, but conventional subcloning methods often fail. We report a rapid and versatile method to subclone PCR products directionally into a specific site of virtually any plasmid vector. The procedure requires only four primers, does not require DNA ligase, and may be accomplished in a single day. Ligase-free subcloning is performed by incorporating into the PCR primers sequences at the 5' ends that result in PCR products whose 3' ends are complementary to the 3' ends of the recipient linearized plasmid. The PCR product and the linearized plasmid are spliced together in a second PCR reaction in which Taq polymerase extends the complementary overlapping 3' ends (ligation by overlap extension). Denaturation followed by heterologous reannealing and cyclization results in a cyclic recombinant plasmid with two nicks that may be used directly to transform competent Escherichia coli. In our hands, ligase-free subcloning is rapid, and offers many advantages over existing strategies.

Bacteriophage lambda↗
PubMed1991

Renal accumulation and urinary excretion of cisplatin in diabetic rats.

Previous work has demonstrated that cisplatin nephrotoxicity was attenuated in streptozotocin (STZ)-induced diabetic rats. The following studies investigated the hypothesis that renal cisplatin accumulation was reduced in diabetic rats. Male Fischer 344 (F344) rats were injected with 32 mg/kg STZ (i.p.) or citrate buffer. Renal platinum (Pt) accumulation was quantitated 0-96 h after the administration of 5 mg/kg cisplatin (i.p.) to normoglycemic and diabetic rats (greater than or equal to 4/group). Total renal Pt accumulation was decreased (P less than 0.05) in the diabetic rats, when compared to the normoglycemic group, 6-48 h after cisplatin injection. Further studies were also conducted to examine if urinary cisplatin excretion was enhanced in diabetic relative to normoglycemic groups. Urinary Pt excretion was quantitated 0-96 h following cisplatin (5 mg/kg, i.p.) administration. Pt excretion was increased in the diabetic group relative to the normoglycemics when comparisons were made on the basis of Pt excreted per hour or cumulative Pt excretion. Differences were also detected in urinary Pt concentration. The diabetic group had a lower urinary concentration of the metal 12-96 h after cisplatin injection. These findings suggest that the reduction in nephrotoxicity in diabetic rats may be at least partially due to decreased renal accumulation as well as altered renal excretion.

Animals↗
PubMed1990

Evidence that Xenopus laevis contains two different nonallelic insulin-like growth factor-I genes.

Using the polymerase chain reaction (PCR), we have amplified and characterized partial nucleotide sequences of two distinct insulin-like growth factor-I genes (designated IGF-I' and IGF-I") from the amphibian, Xenopus laevis. The amplified fragments encoded much of the coding region of the mature peptide (exon III in mammalian IGF-I genes), and exhibited 93% similarity to each other, and 68-82% similarity to mammalian IGF-I amino acid sequences. Southern blot analysis using genomic DNA from a homozygous frog revealed that these two genes are nonallelic in a single organism, like the two nonallelic genes encoding Xenopus insulins that we have characterized previously. Furthermore, both IGF-I mRNAs are expressed in similar quantities in adult liver.

Alleles↗
PubMed1990

Analysis of breathing patterns in a prospective population of term infants does not predict susceptibility to sudden infant death syndrome.

Oscillatory patterns in ventilation have been seen in term and premature infants and are indicative of the stability of the respiratory blood gas feedback control system. Apneas are related to these patterns and apnea duration is correlated with pattern characteristics. In our study breathing patterns were analyzed in recordings from 10 term infants who subsequently died of sudden infant death syndrome (SIDS) and 10 control infants matched for birth wt, gestational age, and postnatal age. Subjects were drawn from a prospectively studied population of 9856 infants. Breath-by-breath minute ventilation was estimated in each of these 24-h recordings and oscillatory patterns were detected using a comb of digital bandpass filters. Confidence limits on the filter output and a bad data flag for rejection of data during gross body movements or crying insured that only significant patterns in ventilation were evaluated. Pattern prevalence and amplitude were compared in three frequency regimes: 6- to 87-s cycle times, 6- to 28-s cycle times, and 28- to 87-s cycle times. There was no significant difference between the SIDS and the control infants in any of these pattern comparisons (paired t and Wilcoxon paired rank sum tests, p less than 0.05). In light of the normal breathing patterns found in the SIDS infants, it is unlikely that susceptibility to SIDS is distinguished, at the time of these recordings, by instability of the respiratory blood gas feedback control system.

Female↗
PubMed1989

Attenuation of cisplatin nephrotoxicity by streptozotocin-induced diabetes.

The therapeutic use of cisplatin is associated with acute renal failure. The purpose of this study was to determine (a) if streptozotocin (STZ) was toxic to renal proximal tubules and (b) the nephrotoxicity of cisplatin in STZ-diabetic rats. Male Sprague-Dawley rats were injected with STZ (55 mg/kg, ip) to induce a diabetic state. BUN and renal cortical slice uptake of p-aminohippurate (PAH) and tetraethylammonium (TEA) were not altered, relative to normoglycemic rats, 3, 16, and 28 days following STZ treatment. These results indicate that STZ is not toxic to renal proximal tubules. Cisplatin nephrotoxicity studies were then conducted in STZ-diabetic and normoglycemic rats. Cisplatin nephrotoxicity was also evaluated in diabetic rats pretreated for 8 days with insulin. Diabetic and normoglycemic rats were administered 5 mg/kg cisplatin or water (ip). Increased kidney weight, BUN levels, glucosuria, and proteinuria were measured in normoglycemic rats 4 days after cisplatin administration. Renal cortical TEA and lactate-stimulated PAH uptake (p less than 0.05) were diminished in the normoglycemic rats 4 days after cisplatin injection. No change in kidney weight, BUN levels, or renal cortical slice accumulation of PAH and TEA was observed in diabetic rats treated with cisplatin. However, cisplatin administration to diabetic rats pretreated with insulin resulted in increased mortality, proteinuria, glucosuria and elevated kidney weight. These results indicate that the diabetic state attenuates cisplatin nephrotoxicity. Additionally, these results indicate that diabetes attenuation of cisplatin nephrotoxicity is dependent on the severity of the diabetic state.

Animals↗
PubMed1988

Prevalence of depression in general practice patients over 75 years of age.

The prevalence of depression among 74 male and 211 female patients aged 75 years or over registered with a group general practice was assessed, using the geriatric depression scale. Test scores of 0- 10, suggesting no depressive illness, were observed in 63 (85%) men and 172 (82%) women. Mild depression (scores 11-20) was observed in 10 (14%) men and 36(17%) women and severe depression (scores 21-30) in one (1%) man and three (1%) women. No significant statistical association was found with age or sex, suggesting that elderly men and women are equally prone to depression.A general practitioner found clinical manifestations of depression in 29 of the patients (10%). The geriatric depression scale scores were compared with clinical diagnoses of depression. Those with high scores were more likely to be depressed and vice versa. Thirty two elderly patients (11%) with no clinical manifestation of depression recorded high scores on the geriatric depression scale. These patients may be described as ;psychiatric cases'. Uncertainty about the importance of early identification of these cases necessitates further screening and regular follow-up of elderly patients.

Aged↗
PubMedDate not supplied

Influence of streptozotocin (STZ)-induced diabetes, dextrose diuresis and acetone on cisplatin nephrotoxicity in Fischer 344 (F344) rats.

The following studies examined the impact of the diabetic state on cisplatin nephrotoxicity. This study also investigated the potential mechanisms for diabetes mediated reduction of cisplatin toxicity. A diabetic state was induced in male Fischer 344 (F344) rats after intraperitoneal (i.p.) injection of 27-35 mg/kg STZ. Cisplatin (5 mg/kg, i.p.) nephrotoxicity was examined in normoglycemic and diabetic rats after 48 and 96 h. Cisplatin was nephrotoxic within 96 h to normoglycemic animals as indicated by an increased kidney weight, marked elevations in serum BUN levels as well as significant P less than 0.05) decreases in renal cortical slice accumulation of p-aminohippurate (PAH) and tetraethylammonium (TEA). Cisplatin failed to depress renal cortical slice accumulation of PAH and TEA in the diabetic rats. Cisplatin was also less effective in increasing BUN levels or kidney weight in diabetic rats. Further studies investigated the impact of glycosuric diuresis and ketone bodies on cisplatin nephrotoxicity. Dextrose diuresis of normoglycemic rats failed to reduce the effect of cisplatin on BUN levels, kidney weight and renal cortical slice uptake of PAH and TEA. Acetone pretreatment of normoglycemic rats also did not reduce cisplatin nephrotoxicity. These results indicate: (1) cisplatin nephrotoxicity is attenuated in the experimental diabetic state, (2) diabetes does not reduce cisplatin nephrotoxicity through glycosuric diuresis and (3) ketone body accumulation does not modulate cisplatin nephrotoxicity.

Acetone↗