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S Holland

Publications and source records attributed to S Holland.

At least 19 recordsLinked to original sources
PubMed2026

A profile of firearm-related fatalities admitted to the Diepkloof Forensic Pathology Service Soweto medico-legal mortuary during the COVID-19 and post COVID-19 periods.

This retrospective descriptive study examined firearm-related fatalities during (April-December 2020; n&#x2009;=&#x2009;241) and after (April-December 2023; n&#x2009;=&#x2009;299) COVID-19 lockdowns using 540 cases from the Diepkloof Forensic Pathology Service, Soweto, South Africa. Data was obtained from autopsy reports, forensic records, police statements, and death scene documentation. Firearm violence affected young adult Black males (22-43&#x2009;years), with only minor demographic shifts post-pandemic. The overall burden and core patterns of violence remained stable, with criminal activity - primarily robbery and interpersonal violence - persisting as the leading contexts, and homicide the dominant manner of death. Post-COVID-19 findings demonstrated contextual shifts, including increased incidents in public and social environments, reflecting greater mobility and resumption of social activity. A significant rise in mean blood alcohol concentration (0.09&#x2009;g/100&#x2009;mL vs 0.14&#x2009;g/100&#x2009;mL; p&#x2009;<&#x2009;0.0001) suggests increased alcohol involvement following easing of restrictions. Unfortunately, persistent information gaps, noted particularly in circumstantial history, incident location, firearm type, highlighting the need for improved data provision and capture systems. While the epidemiology of firearm-related fatalities remained unchanged, the post-COVID-19 period was characterised by increased alcohol involvement, shifts toward public-space violence, and fewer gunshot wounds per victim, suggesting changes in situational and behavioural dynamics rather than underlying drivers of violence.

Humans↗
PubMed2026

A profile of suspected female homicide cases at the Johannesburg and Diepkloof Forensic Pathology Service Medico-legal Mortuaries for 2020-2022.

This study profiles suspected female homicide victims in Johannesburg, South Africa, during the COVID-19 period marked by socio-environmental changes from lockdown restrictions. Guided by the Socio-Ecological Model, a retrospective case series of 369 victims was reviewed using medico-legal mortuary records from Johannesburg and Diepkloof Forensic Pathology Service facilities. Descriptive analyses were conducted, supplemented by a chi-square test to assess whether distributions of causes of death among women differed between COVID-19 and non-COVID-19 periods. No statistically significant association was found, &#x3c7;2 (6, N&#x2009;=&#x2009;339) = 6.68, p&#x2009;=&#x2009;0.35. Key findings highlight that Black, unemployed, unmarried women aged 21-40 were at greatest risk. Cause of death was established in 97.0% (358/369) of cases, with firearm injuries predominating (43.9%), followed by sharp&#x2011;force (24.5%) and blunt&#x2011;force trauma (13.1%). Approximately 90% of victims were suspected to have been killed by males, with half of deaths attributed to intimate partner violence. Homicide frequency decreased during strict lockdowns but rose as restrictions eased, suggesting that movement and alcohol controls may reduce risk. Despite temporary disturbance caused by COVID&#x2011;19 restrictions, the underlying risk profile of female homicide victims remained unchanged. These findings inform multi-level prevention and intervention strategies in South Africa.

Humans↗
PubMed2026

A profile of deaths in children at the Diepkloof Forensic Pathology Services mortuary in Gauteng, South Africa from 1 January 2019 to 31 December 2020.

This retrospective study was conducted to address the scarcity of knowledge regarding unnatural child deaths in South Africa. This was done by analysing cases admitted to the Diepkloof Forensic Pathology Services mortuary between 1 January 2019 and 31 December 2020. Data from FPS death registers and FPS case files were used to profile: (1) the incidence, causes and manner of death, circumstances of death, and ancillary investigations performed at autopsy; and (2) to assess the impact of the COVID-19 pandemic on trauma-related child deaths. Of 4&#x202f;704 decedents, 535 (11.4%) were children, predominantly male (55.5%) and Black (94.8%). Accidental deaths were the most common manner of death (42.6%), primarily due to road traffic accidents, burns, and aspiration. Homicides accounted for 6.5% of all deaths in children, most frequently involving sharp force or gunshot injuries. Cranio-cerebral injuries predominated in trauma-related deaths. In 2020, compared to preceding years, with the implementation of the COVID-19 restrictions, there was a decrease in trauma-related child fatalities. These findings suggest that many child deaths are potentially preventable through government implementation of improved safety interventions and community education.

Humans↗
PubMed2026

A profile of abandoned fetal and neonatal remains admitted to the Diepkloof forensic pathology service medico-legal mortuary during the COVID-19 and post-COVID-19 periods.

The abandonment of neonates is a global concern, with a higher prevalence of cases present in South Africa. This study aimed to review cases admitted to the Diepkloof Forensic Pathology Service during the COVID-19 (2020-2021) and post-COVID-19 (2023) periods. A total of 158 cases were analysed to determine prevalence, demographic characteristics, circumstances and causes of death, with a comparative analysis between the COVID-19 and post-COVID-19 periods. Most cases were classified as natural. However, many were undetermined due to decomposition. Non-viable fetuses (< 26 wk gestation) comprised 47% of the cases. Among the viable births (n&#x2009;=&#x2009;72), 23 (32%) were classified as stillbirths, while 11 (15%) were live births. A minority of cases were deemed unnatural, with deaths attributed to trauma (8 cases) or abandonment (2 cases). No statistically significant difference was found between the COVID-19 and post-COVID-19 periods. Decedents were most often found in open spaces, roads or streets, or dumping sites, most commonly wrapped in plastic materials. These findings highlight the severity of fetal and neonatal abandonment. They underscore a pressing need for targeted preventative measures, community outreach, and enhanced support systems in maternal healthcare to address this growing concern.

Humans↗
PubMed2005

Resonances in ferromagnetic gratings detected by microwave photoconductivity.

We investigate the impact of microwave excited spin excitations on the dc charge transport in a ferromagnetic (FM) grating. We observe both resonant and nonresonant microwave photoresistance, which are caused, respectively, by spin and charge dissipations of the microwave power into the FM. A macroscopic model based on Maxwell and Landau-Lifschitz equations reveals the mixing of spin and charge dissipations, which shows that the ferromagnetic anti-resonance is shifted when the conductivity is anisotropic. We find that the microwave photoconductivity provides a powerful new tool to study the interplay between photonic, spintronic, and charge effects in FM microstructures.

Journal Article↗
PubMed2004

Quantized dispersion of two-dimensional magnetoplasmons detected by photoconductivity spectroscopy.

We find that the long-wavelength magnetoplasmon, resistively detected by photoconductivity spectroscopy in high-mobility two-dimensional electron systems, deviates from its well-known semiclassical nature as uncovered in conventional absorption experiments. A clear filling-factor dependent plateau-type dispersion is observed that reveals a so far unknown relation between the magnetoplasmon and the quantum Hall effect.

Journal Article↗
PubMed2004

Comparative disposition of [14C]ertapenem, a novel carbapenem antibiotic, in rat, monkey and man.

1. The disposition and metabolism of ertapenem, a carbapenem antibiotic, was examined in rat, monkey and man. Sprague-Dawley rats and Rhesus monkeys were given, by intravenous administration, radiolabelled doses of ertapenem (60 and 30 mg kg(-1), respectively), and healthy normal volunteers received a single fixed dose of 1000 mg. Urine and faeces were collected for determination of total radioactivity. 2. In healthy volunteers, [14C]ertapenem was eliminated by a combination of hydrolytic metabolism to a beta-lactam ring-opened derivative and renal excretion of unchanged drug. Approximately equal amounts were excreted as a beta-lactam ring-opened metabolite and unchanged drug (36.7 and 37.5% of dose, respectively). A secondary amide hydrolysis product accounted for about 1% of the dose in man. About 10% of the administered radioactivity was recovered in faeces, which suggested that a minor fraction underwent biliary and/or intestinal excretion. 3. In animals, a greater fraction of the dose was eliminated via metabolism; excretion of unchanged drug accounted for 17 and 5% of dose in rats and monkeys, respectively. In monkeys, the beta-lactam ring-opened and amide hydrolysis metabolites accounted for 74.8 and 7.59% of the dose, respectively, whereas in rats, these metabolites accounted for 31.9 and 20% of dose, respectively. 4. In vitro studies with fresh rat tissue homogenates indicated that lung and kidney were the primary organs involved in mediating formation of the beta-lactam ring-opened metabolite. The specific inhibitor of dehydropeptidase-I, cilastatin, inhibited the in vivo and in vitro metabolism of ertapenem in rats, which suggested strongly that the hydrolysis of ertapenem in lung and kidney was mediated by this enzyme.

Adult↗
PubMed2004

Pharmacokinetics of total and unbound ertapenem in healthy elderly subjects.

Ertapenem is a new once-a-day parenteral carbapenem antimicrobial agent. The pharmacokinetics of unbound and total concentrations of ertapenem in plasma were investigated in elderly subjects and compared with historical data from young adults. In a single- and multiple-dose study, healthy elderly males and females (n = 14) 65 years old or older were given a 1-g intravenous (i.v.) dose once daily for 7 days. Plasma and urine samples collected for 24 h on days 1 and 7 following administration of the 1-g doses were analyzed by reversed-phase high-performance liquid chromatography. Areas under the concentration-time curve from 0 h to infinity (AUC(0- infinity )) for elderly females and males were similar following administration of 1-g single i.v. doses, and thus, the genders were pooled in subsequent analyses. Concentrations in plasma and the half-life of ertapenem were generally higher and longer, respectively, in elderly subjects than in young adults. The mean AUC(0- infinity ) of total ertapenem in the elderly was 39% higher than that in young subjects following administration of a 1-g dose. The differences were slightly greater for the mean AUC(0- infinity ) of unbound ertapenem (71%). The unbound fraction of ertapenem in elderly subjects ( approximately 5 to 11%) was generally greater than that in young adults ( approximately 5 to 8%). As in young adults, ertapenem did not accumulate upon multiple dosing in the elderly. The pharmacokinetics of ertapenem in elderly subjects, while slightly different from those in young adults, do not require a dosage adjustment for elderly patients.

Adult↗
PubMed2002

Pharmacokinetics of ertapenem in healthy young volunteers.

Ertapenem (INVANZ) is a new once-a-day parenteral beta-lactam antimicrobial shown to be effective as a single agent for treatment of various community-acquired and mixed infections. The single- and multiple-dose pharmacokinetics of ertapenem at doses up to 3 g were examined in healthy young men and women volunteers. Plasma and urine samples collected were analyzed using reversed-phase high-performance liquid chromatography with UV detection. Ertapenem is highly bound to plasma protein. The protein binding changes from approximately 95% bound at concentrations of <50 micro g/ml to approximately 92% bound at concentrations of 150 micro g/ml (concentration at the end of a 30-min infusion following the 1-g dose). The nonlinear protein binding of ertapenem resulted in a slightly less than dose proportional increase in the area under the curve from 0 h to infinity (AUC(0- infinity )) of total ertapenem. The single-dose AUC(0- infinity ) of unbound ertapenem was nearly dose proportional over the dose range of 0.5 to 2 g. The mean concentration of ertapenem in plasma ranged from approximately 145 to 175 micro g/ml at the end of a 30-min infusion, from approximately 30 to 34 micro g/ml at 6 h, and from approximately 9 to 11 micro g/ml at 12 h. The mean plasma t(1/2) ranged from 3.8 to 4.4 h. About 45% of the plasma clearance (CL(P)) was via renal clearance. The remainder of the CL(P) was primarily via the formation of the beta-lactam ring-opened metabolite that was excreted in urine. There were no clinically significant differences between the pharmacokinetics of ertapenem in men and women. Ertapenem does not accumulate after multiple once-daily dosing.

Adult↗
PubMed2001

Redox signaling of the arteriolar myogenic response.

Arteriolar vascular smooth muscle cells (VSMCs) are mechanosensitive, constricting to elevations in transmural pressure (P(TM)). The goal of the present study was to determine using mouse isolated tail arterioles and arteries whether oxidant signaling regulates this myogenic response. In response to P(TM) elevation, VSMCs of arterioles but not arteries generated constriction and increased reactive oxygen species (ROS) activity (using the H(2)O(2)-sensitive probe dichlorodihydrofluorescein). Arterioles had increased expression of NADPH oxidase components compared with arteries. Inhibition of NADPH oxidase, using mice with targeted impairment of enzyme components (p47(phox) or rac1) or diphenyleneiodonium, prevented the pressure-induced generation of ROS. When ROS activity was inhibited, either by inhibiting NADPH oxidase or with N-acetylcysteine, the myogenic constriction was abolished. The myogenic constriction was also inhibited by catalase, which inactivates H(2)O(2), but was unaffected by a cell-permeant mimic of superoxide dismutase (MnTMPyP). alpha(1)-Adrenergic constriction was not associated with altered ROS activity and was not affected by inhibition of NADPH oxidase or ROS. Exogenous H(2)O(2) constricted VSMCs of arterioles but not arteries. Thus, NADPH oxidase and ROS, in particular H(2)O(2), contribute to the myogenic response of arteriolar VSMCs.

Acetylcysteine↗
PubMed2001

Expression of the 53 kD forked protein rescues F-actin bundle formation and mutant bristle phenotypes in Drosophila.

forked mutations affect bristle development in Drosophila pupae, resulting in short, thick, gnarled bristles in the adult. The forked proteins are components of 200-300-microm-long actin fiber bundles that are present transiently during pupal development [Petersen et al., 1994: Genetics 136:173-182]. These bundles are composed of segments of 3-10 microm long, and forked protein is localized along the actin fiber bundle segments and accumulates at the junctions connecting them longitudinally. In the forked mutants, f(36a) and f(hd), F-actin bundles are greatly reduced in number and size, and bundle segmentation is absent. The p-element, P[w(+), falter] contains a 5.3-kb fragment of the forked gene that encodes the 53-kD forked protein [Lankenau et al., 1996: Mol Cell Biol 16:3535-3544]. Expression of only the 53-kD forked protein is sufficient to rescue the actin bundle and bristle phenotypes of f(36a) and f(hd) mutant flies. The 5.3-kb forked sequence, although smaller than the 13-kb region previously shown to rescue forked mutants [Petersen et al., 1994: Genetics 136:173-182], does contain the core forked sequence that encodes actin binding and bundling domains in cultured mammalian cells [Grieshaber and Petersen, 1999: J Cell Sci 112:2203-2211]. These data show that the 53-kD forked protein is sufficient for normal bristle development and that the domains shown previously to be important for actin bundling in cell culture may be all that are required for normal actin bundle formation in developing Drosophila bristles.

Actins↗
PubMed2001

Mutational analysis of patients with p47-phox-deficient chronic granulomatous disease: The significance of recombination events between the p47-phox gene (NCF1) and its highly homologous pseudogenes.

OBJECTIVE: The aim of this study was to determine the molecular basis of p47-phox-deficient chronic granulomatous disease (CGD), the most common autosomal recessive form of the disease. CGD is an inherited condition characterized by defective oxygen radical production due to defects in the phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Mutational analysis of p47-phox-deficient CGD patients previously demonstrated that the majority of patients have a GT dinucleotide (Delta GT) deletion at the start of exon 2, a signature sequence also observed in the highly homologous pseudogenes of NCF1. MATERIALS AND METHODS: We performed genetic analysis of NCF1 and its pseudogenes using genomic DNA in 29 p47-phox-deficient CGD patients from 22 separate families. First-strand cDNA analysis was performed in 17 of the 29 patients. RESULTS: We confirmed the significance of the Delta GT mutation; in 27 of 29 patients, only the Delta GT sequence was detectable. All but one of the 27 had at least one additional signature sequence, specific to the pseudogene, in either intron 1 and/or intron 2. We extended our analysis to look at signature sequence differences in exons 6 and 9 and detected both the wild-type and pseudogene sequences in all patients tested. CONCLUSIONS: Although detection of only Delta GT sequence accounts for over 85% of affected patients, the molecular basis is most likely due to partial cross-over events between the wild-type and pseudogene(s) of p47-phox at different recombination sites. Our results suggest that complete gene conversion or deletion of the p47-phox gene (NCF1) occurs rarely, if it all.

Base Sequence↗
PubMed2001

Inosine-5'-monophosphate dehydrogenase is required for mitogenic competence of transformed pancreatic beta cells.

The relation of inosine-5'-monophosphate dehydrogenase (IMPDH; the rate-limiting enzyme in GTP synthesis) to mitogenesis was studied by enzymatic assay, immunoblots, and RT-PCR in several dissimilar transformed pancreatic ss-cell lines, using intact cells. Both of the two isoforms of IMPDH (constitutive type 1 and inducible type 2) were identified using RT-PCR in transformed beta cells or in intact islets. IMPDH 2 messenger RNA (mRNA) and IMPDH protein were both regulated reciprocally by changes in levels of their end-products. Flux through IMPDH was greatest in rapidly growing cells, due mostly to increased uptake of precursor. Glucose (but not 3-0-methylglucose, L-glucose, or fructose) further augmented substrate uptake and also increased IMPDH enzymatic activity after either 4 or 21 h of stimulation. Serum or ketoisocaproate also increased IMPDH activity (but not uptake). Two selective IMPDH inhibitors (mycophenolic acid and mizoribine) reduced IMPDH activity in all cell lines, and, with virtually identical concentration-response curves, inhibited DNA synthesis (assessed as bromodeoxyuridine incorporation) in response to glucose, serum, or ketoisocaproate. Inhibition of DNA synthesis was reversible, completely prevented by repletion of cellular guanine (but not adenine) nucleotides, and could not be attributed to toxic effects. Despite the fact that modulation of IMPDH expression by guanine nucleotides was readily detectable, glucose and/or serum failed to alter IMPDH mRNA or protein, indicating that their effects on IMPDH activity were largely at the enzyme level. Precursors of guanine nucleotides failed, by themselves, to induce mitogenesis. Thus, adequate IMPDH activity (and thereby, availability of GTP) is a critical requirement for beta-cell proliferation. Although it is unlikely that further increases in GTP can, by themselves, initiate DNA synthesis, such increments may be needed to sustain mitogenesis.

3-O-Methylglucose↗
PubMed2001

Contested commodities at both ends of life: buying and selling gametes, embryos, and body tissues.

This essay examines the increasing commodification of the body with respect to tissues, games, and embryos. Such commodifcation contributes to a diminishing sense of human personhood on an individual level, even as it erodes commitments to human flourishing at the societal level. After the case for social harm resulting from the increasing commodification of the body is made, the question becomes whether that harm is best remedied by following any of three approaches by which government traditionally seeks to promote the flourishing of its citizens. The author concludes that it is not, and that what is needed is a pragmatic and somewhat casuistic approach to the regulation of contested commodities--that which legal scholar Margaret Jane Radin calls "incomplete commodification."

Altruism↗
PubMed2001

Variable-ratio versus variable-interval schedules: response rate, resistance to change, and preference.

Two experiments asked whether resistance to change depended on variable-ratio as opposed to variable-interval contingencies of reinforcement and the different response rates they establish. In Experiment 1, pigeons were trained on multiple random-ratio random-interval schedules with equated reinforcer rates. Baseline response rates were disrupted by intercomponent food, extinction, and prefeeding. Resistance to change relative to baseline was greater in the interval component, and the difference was correlated with the extent to which baseline response rates were higher in the ratio component. In Experiment 2, pigeons were trained on multiple variable-ratio variable-interval schedules in one half of each session and on concurrent chains in the other half in which the terminal links corresponded to the multiple-schedule components. The schedules were varied over six conditions, including two with equated reinforcer rates. In concurrent chains, preference strongly overmatched the ratio of obtained reinforcer rates. In multiple schedules, relative resistance to response-independent food during intercomponent intervals, extinction, and intercomponent food plus extinction depended on the ratio of obtained reinforcer rates but was less sensitive than was preference. When reinforcer rates were similar, both preference and relative resistance were greater for the variable-interval schedule, and the differences were correlated with the extent to which baseline response rates were higher on the variable-ratio schedule, confirming the results of Experiment 1. These results demonstrate that resistance to change and preference depend in part on response rate as well as obtained reinforcer rate, and challenge the independence of resistance to change and preference with respect to response rate proposed by behavioral momentum theory.

Animals↗
PubMed2000

The Late Afterglow and Host Galaxy of GRB 990712.

We present deep Hubble Space Telescope (HST) imaging, as well as ground-based imaging and spectroscopy, of the optical afterglow associated with the long-duration gamma-ray burst GRB 990712 and its host galaxy. The data were obtained 48-123 days after the burst occurred. The magnitudes of the host (R=21.9, V=22.5) and optical afterglow (R=25.4, V=25.8, 47.7 days after the burst) favor a scenario in which the optical light follows a pure power-law decay with an index of alpha approximately -1.0. We find no evidence for a contribution from a supernova like SN 1998bw. This suggests that either there are multiple classes of long-duration gamma-ray bursts or that the peak luminosity of the supernova was more than 1.5 mag fainter than SN 1998bw. The HST images and EFOSC2 spectra indicate that the gamma-ray burst was located in a bright, extended feature (possibly a star-forming region) 1.4 kpc from the nucleus of a 0.2L*B galaxy at z=0.434, possibly a Seyfert 2 galaxy. The late-time afterglow and host galaxy of GRB 990712 bear some resemblance to those of GRB 970508.

Journal Article↗