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Biomedical subjects

D H Harris

Publications and source records attributed to D H Harris.

17 recordsLinked to original sources
PubMed1996

Efficacy of intracytoplasmic sperm injection using intentionally cryopreserved epididymal spermatozoa.

Microsurgical epididymal sperm aspiration was a great advance in the therapy of patients with non-reconstructable, obstructive azoospermia, most notably congenital bilateral absence of the vas deferens. Using conventional in-vitro fertilization, pregnancies were rarely achieved because the rate of oocyte fertilization was extremely poor. However, the use of retrieved spermatozoa in conjunction with intracytoplasmic sperm injection (ICSI) has dramatically increased the likelihood of embryo formation. Typically, sperm and oocyte harvesting are performed simultaneously. We have investigated whether frozen-thawed spermatozoa work as well as fresh spermatozoa. When we had concluded from our own population of patients (groups I and II) that they did, we adopted a policy of aspirating spermatozoa, primarily cryopreserving them and using them for ICSI at a later date. We found the fertilization rates of this latter cohort of patients (group III) to be excellent (37% per oocyte), and the ongoing pregnancy rate is quite satisfactory (40% per couple, 29% per cycle). We offer this approach as an alternative to the traditional scheme because it markedly eases the burden of partner scheduling on both the couple and the clinicians involved. In addition, assurance of the availability of male partner spermatozoa can be attained prior to beginning ovulation induction.

Adult↗
PubMed1995

Sperm morphology and in vitro fertilization outcome: a direct comparison of World Health Organization and strict criteria methodologies.

OBJECTIVE: To perform a direct comparison of two sperm morphology methodologies with regard to IVF outcome. DESIGN: Blinded comparison of two methods of morphology assessment using the same morphology slides. PATIENTS: Data were obtained from 132 couples in a consecutive series of patients undergoing IVF. MAIN OUTCOME MEASURES: Two practical end points were selected for analysis for each couple: the presence of any fertilization and the number of fertilized eggs. Normal traditional morphology was defined as > or = 40% normal forms in a sample and normal strict criteria was defined as > or = 4%. RESULTS: Traditional morphology demonstrated a higher sensitivity and negative predictive value than strict criteria (87% versus 61%, and 68% versus 36%, respectively). Positive predictive value and specificity were also numerically greater but did not reach statistical significance. Abnormal traditional morphology, but not strict criteria, was associated with reduced fertilization even among samples with normal sperm concentration and motility. Samples with normal morphology were associated with a greater number of fertilized eggs per couple than those with abnormal morphology: this difference was 3.2 fertilized eggs for traditional morphology and 1.6 for strict criteria. Overall, for samples with < 40% by traditional morphology only one case yielded more than two fertilized eggs. In contrast, up to five fertilized eggs were noted for the lowest strict criteria scores. CONCLUSIONS: Comparison of traditional morphology and strict criteria with regard to IVF outcome favored traditional morphology in several areas. In particular, low scores were more predictive of poor IVF outcome.

Female↗
PubMed1995

Determination of circulating blood volume by continuously monitoring hematocrit during hemodialysis.

Dialysis-induced hypovolemia occurs because the rate of extracorporeal ultrafiltration exceeds the rate of refilling of the blood compartment. The purpose of this study was to evaluate a method for calculating circulating blood volume (BV) during hemodialysis (HD) from changes in hematocrit (Hct) shortly (2 to 10 min) before and after ultrafiltration (UF) was abruptly stopped. Hct was monitored continuously during 93 HD treatment sessions in 16 patients by an optical technique and at selected times by centrifugation of blood samples. Total plasma protein and albumin concentrations were also measured at selected times. Continuously monitored Hct correlated with Hct determined by centrifugation (R = 0.89, N = 579). Relative changes in BV determined by continuously monitored Hct were not different from those determined by total plasma protein concentration (P = 0.05; N = 273). Calculated BV at the start of dialysis (4.1 +/- 1.3 L) was not different (P = 0.18, N = 12) from that derived anthropometrically from the patient's dry weight (4.6 +/- 0.8 L), and calculated BV when UF was stopped was 3.2 +/- 0.5 L (46 +/- 7 ml/kg body wt). These latter estimates of BV are consistent with those determined previously by dilution techniques in HD patients. It was concluded that (1) relative changes in BV assessed by continuously monitored Hct were unbiased and (2) BV can be determined noninvasively during HD by continuously monitoring Hct and temporarily stopping UF.

Blood Volume↗
PubMed1993

Comparative analysis of the sequence and structure of two Drosophila melanogaster genes encoding vitelline membrane proteins.

Two Drosophila melanogaster vitelline membrane protein-encoding genes (VM), located at polytene band positions 26A and 34C, have been cloned and comparatively characterized at the nucleotide level. Sequence analysis of genomic and cDNA clones for the two genes, VM26A.1 and VM34C.1, indicates that both are similarly organized with a central highly conserved domain [Scherer et al., Dev. Biol. 130 (1988) 786-788] which is flanked by unrelated regions, and that both genes lack introns. Comparison of the upstream regions reveals that both VM genes contain a hepatmeric element identical to one associated with the D. melanogaster yolk protein-encoding genes (YP). This heptamer occurs in the specific 5' flanking region responsible for ovarian temporal- and tissue-specific control in both VM and YP genes. A putative chorion transcription factor 2 site is also associated with an upstream control element of VM26A.1, but not with any sequenced portion of VM34C.1.

Amino Acid Sequence↗
PubMed1989

The Loughborough anthropometric shadow scanner (LASS).

There has been interest in the use of drawing frames and other devices to record the size and shape of the human body since Albrecht Dürer's Vier Bücher von Manschlicher Proportion was published in 1528. Until recently, however, the methods used have been slow and laborious, mostly involving some degree of physical contact. This article describes a fully automated system which is capable of making such measurements quickly, accurately, and comprehensively.

Anthropometry↗
PubMed1988

Drosophila vitelline membrane genes contain a 114 base pair region of highly conserved coding sequence.

Two Drosophila vitelline membrane (VM) genes located at polytene band positions 26A and 34C have been characterized at the nucleotide level. Sequence comparison of the two genes VM26A.1 and VM34C.1 has revealed a similar 114 base pair region centrally located in the coding regions of both genes. The conserved region has a 91% homology at the nucleic acid level and a 100% conservation at the amino acid level. This suggests a common evolutionary origin for these VM genes and indicates that a strong selective pressure exists to maintain a specific polypeptide sequence in a domain of the proteins.

Animals↗
PubMed1977

Acute hemorrhagic conjunctivitis: a mixed virus outbreak among Vietnamese refugees on Guam.

In May 1975 the authors investigated an outbreak of acute hemorrhagic conjunctivitis that affected an estimated 29,000 refugees from South Vietnam who stayed on Guam while en route to the United States. Illness usually lasted6-10 days and was characterized by conjunctival injection (100%), lid edema (84%), eye irritation (81%) and subconjunctival hemorrhages (45%). Conjunctival swabs and paired serum specimens on a limited number of patients implicated enterovirus 70 as a major etiologic agent and adenovirus 11 as a less frequent agent. Adenovirus 8 and herpes simplex virus caused concurrent, sporadic cases of keratoconjunctivitis. Forty-three per cent of the refugees in a sample of 604 refugees were affected, and the attack rate was highest on evacuation vessels where crowding and poor sanitation facilitated person-to-person spread of infection. Because the outbreak subsided on Guam, and because infection was transmitted there to only 13 of about 1300 Americans in frequent contact with affected refugees, the risk of secondary outbreaks inthe United States appeared small.

Acute Disease↗
PubMedDate not supplied

Hematocrit as an indicator of blood volume and a predictor of intradialytic morbid events.

Hematocrit (H) levels can change during hemodialysis, and these changes in H are inversely related to changes in blood volume (BV). The objectives of this study were to determine whether mean arterial pressure (MAP) decreases with decreasing BV and rising H during hemodialysis, and to determine the relationship between dialysis induced intravascular volume depletion and intradialytic morbid events (IME), defined as hypotension, cramping, or lightheadedness that led to dialysis staff intervention. We monitored H continuously using a noninvasive optical technique in 93 hemodialysis sessions in 16 patients. IME occurred in 48 sessions. MAP decreased with increasing H in 10 of 16 patients (P < 0.05), but the relationship between MAP and H varied among the patients. The rate of BV change during sessions without morbidity (5.6 +/- 3.6 [SD] %/hr) was lower (P < 0.001) than that preceding IME in the other sessions (12.2 +/- 5.5 [SD] %/hr). Twelve of 16 patients who exhibited recurrent IME during this study experienced these events when H reached a patient specific threshold. It is concluded that MAP decreases with decreasing BV and increasing H in many patients on hemodialysis, and that a high rate of BV change often indicates that IME are forthcoming. It is further hypothesized that a patient specific H threshold is indicative of a critical BV level below which certain patients experience IME.

Blood Pressure↗