Differential pulse oximetry readings between ethnic groups and delayed transfer to intensive care units

BACKGROUND

Pulse oximeters are widely used to monitor blood oxygen saturations, although concerns exist that they are less accurate in individuals with pigmented skin.

AIMS

This study aimed to determine if patients with pigmented skin were more severely unwell at the period of transfer to intensive care units (ICUs) than individuals with White skin.

METHODS

Using data from a large teaching hospital, measures of clinical severity at the time of transfer of patients with COVID-19 infection to ICUs were assessed, and how this varied by ethnic group.

RESULTS

Data were available on 748 adults. Median pulse oximetry demonstrated similar oxygen saturations at the time of transfer to ICUs (Kruskal-Wallis test, P = 0.51), although median oxygen saturation measurements from arterial blood gases at this time demonstrated lower oxygen saturations in patients classified as Indian/Pakistani ethnicity (91.6%) and Black/Mixed ethnicity (93.0%), compared to those classified as a White ethnicity (94.4%, Kruskal-Wallis test, P = 0.005). There were significant differences in mean respiratory rates in these patients (P < 0.0001), ranging from 26 breaths/min in individuals with White ethnicity to 30 breaths/min for those classified as Indian/Pakistani ethnicity and 31 for those who were classified as Black/Mixed ethnicity.

CONCLUSIONS

These data are consistent with the hypothesis that differential measurement error for pulse oximeter readings negatively impact on the escalation of clinical care in individuals from other than White ethnic groups. This has implications for healthcare in Africa and South-East Asia and may contribute to differences in health outcomes across ethnic groups globally.

46 The Accuracy of Frailty Scoring and Uptake of Comprehensive Geriatric Assessment (CGA) In Patients Living with Frailty Admitted Through the Emergency Department (ED) In Wythenshawe Hospital

Introduction

Frailty can be defined as a state of physiological decline related to ageing and its identification is crucial for subsequent management. A Cochrane review found that CGA significantly reduces mortality and institutionalisation at 6 months.1 Published standards for the hospital state that patients with a clinical frailty score (CFS) of ≥7 should be seen by a geriatrician within one hour of presentation to hospital. We investigated if this was met.

Methods

Assigning a CFS to all patients ≥65 was introduced to ED triage in November 2018. Patients scored as ≥4 were identified over a 10-day period. We assessed the accuracy of ED based frailty scoring, subsequent hospital wide CGA uptake and investigated if patient’s frailty scores influenced this. We also compared CGA uptake across specialities.

Results

Over 10 days, 230 patients entering ED were identified as frail. 33% of patients received CGA. On average, it took 18 hours for a patient to get CGA, and 23 hours for a patient with a CFS ≥7 to receive CGA from a geriatrician. The CFS had no influence on them receiving CGA. Surgical specialities were better than some medical specialities in assessing frailty. 38% of the patient’s CFS were correct.

Conclusions

The hospital is falling short of the standards set out by the department; suggesting that changes need to be made to the process of CGA. There is currently no hospital-wide proforma for CGA; collecting data on the process is laborious and the triggers for CGA are not working as they should. Adding CGA to the hospital EPR would improve this. Highlighting the patients CFS will encourage referral for CGA. Specialities such as cardiology and respiratory can learn from the systems for the recognition and assessment of frailty in place on surgical wards.

Reference

1. Ellis, et al. Cochrane Review 2017.

Atypical Schwannoma: A 10-year experience

OBJECTIVE

The goal of this study was to describe the clinical presentation associated with atypical schwannoma of the cerebellopontine angle, characterize the pathologic findings and describe the long-term outcome.

MATERIALS AND METHODS

The study design was retrospective case review of patients with the histopathologic diagnosis of atypical and benign schwannoma of the cerebellopontine angle diagnosed at the study institution over a 10-year period.

SETTING

Tertiary referral center.

MAIN OUTCOMES MEASURE

Demographic data of the cohort were recorded. Findings on pathology were evaluated. Initial treatment and post-operative course was recorded. Main outcome measures were clinical presentation, including cranial nerve deficits at the time of presentation, complication and recurrence rates.

RESULTS

At presentation, a somewhat accelerated course of cranial nerve deficit was noted among patients with atypical schwannoma as compared to benign schwannoma. In the immediate post-operative period, there were no differences noted in the complication rate. Atypical schwannomas appear to have higher recurrence rate compared to benign schwannomas.

CONCLUSIONS

Atypical schwannoma is an intermediate disease process with an accelerated clinical course and higher recurrence rate as compared to vestibular schwannoma. Traditional operative approaches may be employed without increased concern for post-operative complications. Thorough counseling and close follow-up should be offered to these patients given the higher recurrence rate. Larger studies are required to determine if these patients need more frequent MRIs for long-term surveillance.

The role of citizen science in addressing grand challenges in food and agriculture research

The power of citizen science to contribute to both science and society is gaining increased recognition, particularly in physics and biology. Although there is a long history of public engagement in agriculture and food science, the term 'citizen science' has rarely been applied to these efforts. Similarly, in the emerging field of citizen science, most new citizen science projects do not focus on food or agriculture. Here, we convened thought leaders from a broad range of fields related to citizen science, agriculture, and food science to highlight key opportunities for bridging these overlapping yet disconnected communities/fields and identify ways to leverage their respective strengths. Specifically, we show that (i) citizen science projects are addressing many grand challenges facing our food systems, as outlined by the United States National Institute of Food and Agriculture, as well as broader Sustainable Development Goals set by the United Nations Development Programme, (ii) there exist emerging opportunities and unique challenges for citizen science in agriculture/food research, and (iii) the greatest opportunities for the development of citizen science projects in agriculture and food science will be gained by using the existing infrastructure and tools of Extension programmes and through the engagement of urban communities. Further, we argue there is no better time to foster greater collaboration between these fields given the trend of shrinking Extension programmes, the increasing need to apply innovative solutions to address rising demands on agricultural systems, and the exponential growth of the field of citizen science.

Screening for latent tuberculous infection in people living with HIV infection in Auckland, New Zealand

SETTING

New Zealand, which has a low incidence of tuberculosis (TB), has historically taken a risk-based approach to screening for latent tuberculous infection (LTBI) in adult people living with the human immunodeficiency virus infection (PLHIV).

OBJECTIVE

To evaluate LTBI screening, treatment and outcomes in an adult PLHIV population.

DESIGN

This was a retrospective clinical record review of an initial cohort of adult PLHIV attending the Auckland City Hospital HIV clinic in 2011, and a second cohort of adult PLHIV newly attending the clinic in 2014. We analysed high-risk (born in or acquiring HIV in a high TB incidence country) and low-risk patients using descriptive statistical methods.

RESULTS

Of the 752 patients from the initial cohort, 416 (55%) had documentation of LTBI screening, which was positive in 74 (10%): 19/461 (4%) low-risk and 55/291 (19%) high-risk patients. LTBI treatment was received in 13 low-risk and 44 high-risk patients. Of 73 patients in the second cohort, 68 (93%) were screened.

CONCLUSION

LTBI screening was incomplete in our clinic, but improved between 2011 and 2014. A significant number of patients with LTBI did not originate from a high TB incidence country.

Medical and bioethical considerations in elective cochlear implant array removal

OBJECTIVE

Cochlear explantation for purely elective (e.g. psychological and emotional) reasons is not well studied. Herein, we aim to provide data and expert commentary about elective cochlear implant (CI) removal that may help to guide clinical decision-making and formulate guidelines related to CI explantation.

DATA SOURCES

We address these objectives via three approaches: case report of a patient who desired elective CI removal; review of literature and expert discussion by surgeon, audiologist, bioethicist, CI user and member of Deaf community.

REVIEW METHODS

A systematic review using three scientific online databases was performed. Included articles addressed the benefits and/or complications of cochlear implantation in young children, CI explantation with or without revision surgery and the ethical debate between the medical and Deaf communities on cochlear implantation and explantation.

CONCLUSIONS

The medical and audiological perspectives identify a host of risks related to implant removal without reimplantation, including risk from surgery, general anaesthesia, cochlear ossification and poor audiometric outcomes. The member of the deaf community and bioethicist argue that physicians need to guide the principles of beneficence, non-maleficence and patient autonomy. Taken together, patient desires should be seen as paramount, if the patient is otherwise fit for surgery and well informed.

IMPLICATIONS FOR PRACTICE

Similar to the case of device implantation, device explantation should be a multidisciplinary and collaborative decision with the patient and the family's desires at the centre. While every case is different, we offer a CI explantation discussion to assist in clinical decision-making, patient counselling and education.

Practitioners' experiences of adolescent suicidal behaviour in peer groups

WHAT IS KNOWN ON THE SUBJECT?: Group suicidal behaviour can be devastating for all concerned. There is an absence of research on adolescent suicidal group behaviour. The perspectives of practitioners' experiences of these groups are largely lacking from research literature. WHAT THIS PAPER ADDS TO EXISTING KNOWLEDGE?: Practitioners work regularly with suicidal behaviour in adolescent peer groups. Practitioners identify peer relationships in groups as complex, including elements that are both suicide encouraging and preventing. Practitioners identify a range of ways in which young people become involved in suicidal behaviour in groups, including indirectly through risk taking and care-seeking as well as directly suicidal or self-harming. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: Assessments of young people should routinely include a focus on the qualities of peer relations, including those in the online/digital realm. Assessments and interventions need to consider the complexity of group relationships and roles, and the multiplicity of factors that can contribute to suicidal behaviour in groups. Interventions that sustain therapeutic connectedness are helpful for taking dynamic/fluctuating risks into account.

ABSTRACT

Introduction Group suicidal behaviour by young people can have harmful effects; it may be increasing, influenced by online media and reported increasing self-harm rates; new knowledge and understanding to inform interventions is required. Aim To explore how practitioners experience group suicidal behaviour amongst adolescents, how they assess risks/needs, and how these insights inform understanding about these groups. Method Ten practitioners, including Mental Health Nurses, were interviewed in one multidisciplinary CAMHS, in England. Data analysis was by Thematic Analysis (Braun & Clarke 2006). Results Participants described frequently working with suicidal groups. Roles in groups include suicide encouraging and preventing. Practitioners identify risky and protective connections between young people, online and offline. Clinical tensions include living with suicidal risks, emotional and positional challenges, and getting to grips with digital media. Discussion Peer groups appear to have a larger role in adolescent suicide than recognized to date. Practitioners need to assess young people's roles in groups, their diverse motivations and to understand constantly changing digital media. Implications for practice Assessments of suicide risk for young people should routinely include focus on peer relations including the online/digital realm. Maintaining relationships with vulnerable young people facilitates managing fluctuating risks and understanding different group dynamics.

Short-course intravenous aciclovir treatment for cutaneous herpes zoster in patients with HIV infection

There are no comparative data on the treatment duration of cutaneous herpes zoster (HZ) in patients with HIV infection. We retrospectively reviewed all 51 adult patients with HIV infection presenting with cutaneous HZ in the 15-year period 1995-2009 treated with intravenous aciclovir alone. The median CD4 count was 297 (range 10-703) cells/mm(3). There were 44 episodes of localized and seven episodes of disseminated cutaneous HZ. Patients received a median of nine (range 3-17) doses of intravenous aciclovir given at a median dose of 6.5 (range 2.9-10.8) mg/kg eight hourly. One patient (2%) relapsed early and four patients (7.8%) relapsed late with further episodes of cutaneous HZ. Seven patients (13.7%) developed postherpetic neuralgia. Three days of intravenous aciclovir is effective treatment for cutaneous HZ in patients with HIV infection.

An audit of patients investigated by Hysterosalpingo-Contrast-Sonography (HyCoSy) for infertility

We reviewed 171 case notes of patients investigated by HyCoSy for sub-fertility in South Manchester University Hospital to assess HyCoSy as a screening test for tubal occlusion, in low risk infertile women and to evaluate the performance of HyCoSy in our unit by confirming its results with the results of laparoscopy & dye test in those patients who had both procedures. We also assessed the prognostic significance of HyCoSy, for fertility outcome over a follow-up period ranging from 12 to 63 months. An audit proforma was designed to collect data on maternal age, type of infertility (primary or secondary), duration of infertility and parity. History suggestive of ovulatory factors (PCO), pelvic inflammatory disease and endometriosis was noted. Findings of standard trans-vaginal scan, hysterosalpingography and HyCoSy were recorded. In total 333 tubes were examined in 171 patients. There were 121/171 diagnoses of bilateral patent tubes, 24/171 bilateral blocked tubes and 26/171 findings of one patent tube. In 15 (8.8%) women, laparoscopy and dye test was performed after HyCoSy and 19 patients had laparoscopy and dye test before HyCoSy. The findings in both investigations were similar. 70 additional uterine and adnexal pathologies were detected. Out of 171 40.9% (n=70) women conceived, 62 of these women had both tubes patent and 8 had one patent tube. In conclusion we have found that HyCoSy is a valuable cost effective screening test for low risk couples. Its results in our hands are as good as demonstrated by other studies. HyCoSy can be offered as a screening test for low risk infertile women as it is an effective alternative for laparoscopy and dye test.

Increased Resistance of DNA Lipoplexes to Protein BindingIn Vitroby Surface-modification with a Multivalent Hydrophilic Polymer

The potential of cationic liposomes as DNA delivery vehicles for gene therapy is significantly limited by their instability upon systemic administration. Their strong positive charge induces non-specific binding of serum proteins and subsequent clearance from the circulation. This work investigates the ability of the multivalent reactive copolymer of poly[N-(2-hydroxypropopyl) methacrylamide], pHPMA (MA-GG-ONp) to shield lipoplexes from non-specific protein binding. The polymer was found to react with cationic liposome-DNA complexes (lipoplexes) in both an electrostatic and covalent manner to form an external polymer coat. Polymer coating resulted in an increase in lipoplex diameter (by up to 100 nm) that was proportional to the amount of polymer used, with a concomitant reduction in surface charge from strongly positive to neutral (from 30 to 0 mV). Polymer-coated lipoplexes exhibited increased stability to protein binding compared to untreated liposomes and reduced non-specific uptake into cells in vitro.

Extended-spectrum beta-lactamase (ESBL)-producing enterobacteria: factors associated with infection in the community setting, Auckland, New Zealand

We aimed to document the epidemiology of extended-spectrum beta-lactamase (ESBL)-producing enterobacteria in the Auckland community and identify factors associated with infection using a case-control study design. ESBL-producing enterobacteria were isolated from 107 infected patients, for which demographic and clinical data were available for 98 cases (92%). Escherichia coli was the predominant organism (82%), with urine as the commonest source (97%). Compared with a control group infected with ESBL-negative enterobacteria, factors significantly associated with infection on univariate analysis were: living in a residential care home (RCH); recent admission to hospital 'M'; recent antibiotic use; older age (>75 years); presence of a urinary catheter; and a history of comorbid chronic obstructive pulmonary disease (COPD), cardiovascular disease, neurological disease or recurrent urinary tract infection. On multivariate analysis, residence in RCH and COPD remained significant associations. Pulsed-field gel electrophoresis typing of the ESBL-producing E. coli identified a common strain. We concluded that residence in RCH and a history of COPD are significant associations with ESBL-producing enterobacterial infection in the Auckland community. Several spatial clusters in RCHs and a common strain suggest point-source outbreaks. A substantial number of community cases did not live in an RCH nor had been recently hospitalised, suggesting the independent generation of ESBL-producing enterobacteria in the broader community.

Propionibacterium acnes: an under-appreciated cause of post-neurosurgical infection

BACKGROUND

Propionibacterium acnes is increasingly recognized as a cause of post-neurosurgical infection. This review of patients with P. acnes neurosurgical infection was carried out in order to determine clinical characteristics and outcomes in relation to duration of antimicrobial treatment.

METHODS

We retrospectively reviewed the charts of consecutive patients with P. acnes isolated from neurosurgical specimens from 1 January 1999 to 30 June 2005. We defined P. acnes neurosurgical infection as isolation of P. acnes alone from a sterile neurosurgical site in a patient who clinically improved following treatment with an appropriate antibiotic.

RESULTS

We identified 28 patients with definite P. acnes neurosurgical infection; median age 49 years (range 23-77); 15 (54%) male. All patients had prior neurosurgical procedures: 27 (96%) post-craniotomy. The median time from surgery to presentation was 54 days (range 12-1,578). Eighteen out of 28 (64%) patients who met the definition of neurosurgical infection had Gram-positive bacilli seen in at least one surgical specimen compared with only 2/56 (4%) patients who did not meet the definition (P < 0.0001). Intravenous benzyl penicillin +/- oral penicillin VK was the most common treatment. The median duration of antibiotic treatment for intracranial infection was 29 days. Five of nine patients who had extracranial bone-flap-associated infection had <or=7 days of intravenous treatment and were cured. Two patients had relapse or reinfection.

CONCLUSIONS

P. acnes neurosurgical infection often presents in an indolent fashion. Gram-positive bacilli on Gram stain should not be discounted as a contaminant in neurosurgical specimens. Associated bone flaps should be removed. Intravenous benzyl penicillin +/- oral penicillin VK remains effective treatment.

What do specialist registrars know about clinical governance?

Clinical governance is an essential part of quality assurance for everyday clinical practice. It is part of the generic curriculum for all specialist registrars (SpRs) training in medical specialities. The authors of this update undertook a survey of SpRs training in geriatric medicine to determine their perceived knowledge of clinical governance and whether they had received training in this area.

Short course intravenous benzylpenicillin treatment of adults with meningococcal disease

BACKGROUND

Short-course treatment of meningococcal disease (including meningitis) with 4-5 days of an i.v. beta-lactam is of proven efficacy. Since April 1998, all adult patients with meningococcal disease admitted to Auckland Hospital were prospectively treated with 3 days of i.v. benzylpenicillin.

AIMS

To assess the clinical features, laboratory findings, disease complications and outcome of patients with meningococcal disease prospectively treated with 3 days of i.v. benzylpenicillin.

METHODS

A retrospective chart review of all adult patients with meningococcal disease admitted to Auckland Hospital from April 1998 to December 2002 was conducted.

RESULTS

Ninety patients with definite (n = 72) or -probable (n = 16) meningococcal disease were admitted during the study period. Two were excluded on the basis of treatment duration. The remaining 88 patients received a mean +/- standard deviation duration of treatment of 3.1 +/- 0.5 days (excluding those who died while receiving treatment). Six patients (7%) died, four of whom while on treatment. There were no relapses.

CONCLUSION

Three days of i.v. benzylpenicillin for the treatment of adults with meningococcal disease is effective.

Determining the relationship between end-of-life decisions expressed in advance directives and resuscitation efforts during cardiopulmonary resuscitation

In recent years, there has been an increased focus on end-of-life decisions and the use of medical technology. It is not well documented in the literature whether or not and to what extent patients' advance directives are used for directing resuscitative efforts. The purpose of this study was to determine how useful patients' advance directives were to members of the health care team in determining treatment and end-of-life decisions among patients who received cardiopulmonary resuscitation (CPR) efforts. Medical records of 135 adult patients who had undergone CPR efforts within the previous year were reviewed to determine if and to what extent advance directives were useful in directing end-of-life care and treatment decisions. Only 35 of these patients had advance directives. Three categories for advance directives emerged: those that were "independently directive," those that were "vague and required further clarification," and those that were "nondirective." Information from this study may be used to clarify treatment options for end-of-life care and to determine if and what further interventions are required to ensure that advance directives can be executed as meaningful documents.

Structure-based design of potent, amidine-derived inhibitors of factor Xa: evaluation of selectivity, anticoagulant activity, and antithrombotic activity

To enhance the potency of 1,2-dibenzamidobenzene-derived inhibitors of factor Xa (fXa), an amidine substituent was incorporated on one of the benzoyl side chains to interact with Asp189 in the S1 specificity pocket. Lead molecule 1 was docked into the active site of fXa to facilitate inhibitor design. Subsequently, iterative SAR studies and molecular modeling led to a 1000-fold increase in fXa affinity and a refined model of the new inhibitors in the fXa active site. Strong support for the computational model was achieved through the acquisition of an X-ray crystal structure using thrombin as a surrogate protein. The amidines in this series show high levels of selectivity for the inhibition of fXa relative to other trypsin-like serine proteases. Furthermore, the fXa affinity of compounds in this series (K(ass) = 50-500 x 10(6) L/mol) translates effectively into both anticoagulant activity in vitro and antithrombotic activity in vivo.

Experimental inoculation of avian polyomavirus in chemically and virally immunosuppressed chickens

The purpose of this series of experiments was to determine the effect of various types of immunosuppressive treatments (cyclophosphamide, infectious bursal disease virus [IBDV], chicken anemia virus [CAV], and combination infection with IBDV and CAV) on susceptibility of chickens to challenge with avian polyomavirus. In the first experiment, chickens were chemically bursectomized with intraperitoneal injections of cyclophosphamide; in the second study, chickens were orally inoculated with IBDV; in the third study, birds were intramuscularly inoculated with CAV; and in the final study, birds were inoculated with both IBDV and CAV. In all experiments, chickens were challenged with 10(4.7) tissue culture infective doses of polyomavirus intraperitoneally. Only chemically bursectomized chickens developed lesions similar to those found in the naturally occurring multisystemic fatal form of polyomavirus infection seen in psittacine nestlings, including hepatic necrosis and large pale intranuclear inclusions.

Acute idiopathic gastric dilation with gastric necrosis in individuals with Prader-Willi syndrome

Individuals with Prader-Willi syndrome (PWS) have excessive appetite with the ability to consume large quantities of food. Absence of vomiting and a high pain threshold are considered manifestations of the disorder. We present 6 patients with PWS with acute dramatic gastric distention. In 3 young adult women with vomiting and apparent gastroenteritis, clinical course progressed rapidly to massive gastric dilatation with subsequent gastric necrosis. One individual died of overwhelming sepsis and disseminated intravascular coagulation. In 2 children, gastric dilatation resolved spontaneously. Gastrectomy specimens--in 2 cases subtotal and distal, in the other with accompanying partial duodenectomy and pancreatectomy--showed similar changes. All cases demonstrated signs of ischaemic gastroenteritis. All specimens showed diffuse mucosal infarction with multifocal transmural necrosis. Vascular dilatation and small bifrin thrombi were apparent within the infarcted areas. These 6 women with PWS had acute idiopathic gastric dilatation. It is possible that a predisposition to acute gastric dilatation may be related to abnormal gastric homeostasis on a genetic basis. Understanding the mechanisms responsible for this event could increase the understanding of gastrointestinal and appetite regulation in individuals with PWS.

Exercise intensity dependent inhibition of 1-methyl-1-nitrosourea induced mammary carcinogenesis in female F-344 rats

The objective of this experiment was to evaluate the effects of treadmill exercise on tumor induction in an experimental model for breast cancer. Female F-344 rats were injected i.p. with 50 mg MNU/kg body wt at 50 and 57 days of age. Animals were assigned to one of five groups: sham exercise or 35% or 70% maximal treadmill running intensity for 20 or 40 min/day, 5 days per week. These work rates represent an exercise intensity level generally considered insufficient to improve cardiovascular fitness (35% maximal intensity) or an aerobic level of exercise sufficient to improve cardiovascular fitness in humans (70% maximal intensity). Rats were exercised for 3 months following carcinogen administration at which time the experiment was terminated. Mammary cancer incidence was reduced by as much as 37% and cancer multiplicity by < 60% at the highest exercise intensity. Unexpectedly, the degree of protection against cancer was proportional to the intensity but not to the duration of exercise.

Two SH2 domains of p120 Ras GTPase-activating protein bind synergistically to tyrosine phosphorylated p190 Rho GTPase-activating protein

p120 GTPase-activating protein (GAP) is a negative regulator of Ras that functions at a key relay point in signal transduction pathways that control cell proliferation. Among other proteins, p120 GAP associates with p190, a GAP for the Ras-related protein, Rho. To characterize the p120.p190 interaction further, we used bacterially expressed glutathione S-transferase fusion polypeptides to map the regions of p120 necessary for its interactions with p190. Our results show that both the N-terminal and the C-terminal SH2 domains of p120 are individually capable of binding p190 expressed in a baculovirus/insect cell system. Moreover, the two SH2 domains together on one polypeptide bind synergistically to p190, and this interaction is dependent on tyrosine phosphorylation of p190. In addition, mutation of the highly conserved Arg residues in the critical FLVR sequences of both SH2 domains of full-length p120 reduces binding to tyrosine-phosphorylated p190. The dependence on p190 phosphorylation for complex formation with p120 SH2 domains observed in vitro is consistent with analysis of the native p120.p190 complexes formed in vivo. These findings suggest that SH2-phosphotyrosine interaction is one mechanism by which the cell regulates p120.p190 association and thus may be a means for coordinating the Ras- and Rho-mediated signaling pathways.

Construction of a reshaped HMFG1 antibody and comparison of its fine specificity with that of the parent mouse antibody

A human antibody with milk mucin specificity was obtained by transferring the complementarity determining regions (CDR) of the mouse antibody HMFG1 onto carefully selected human framework regions. The resulting reshaped human antibody, HuHMFG1, showed no difference in relative affinity for its antigen compared with the parent mouse HMFG1. The minimum epitope recognized by both the mouse and reshaped antibodies was demonstrated by epitope mapping to be identical, and consists of the tetramer PDTR. In a replacement net analysis, in which each of the amino acids was replaced in turn with the 19 other residues, it was determined that mouse HMFG1 and HuHMFG1 reacted with this series of synthetic peptides in an equivalent manner, indicating retention of identical fine specificity in the HuHMFG1 antibody. In contrast to other published reports, this was achieved without involvement of any framework residues in the binding site transfer. These data demonstrate that if well-matching human framework regions are employed grafting the CDR only can be sufficient to confer desired specificities to human antibodies and can, indeed, provide human analogues of mouse antibodies with virtually indistinguishable affinities and fine specificities relative to the mouse parent antibodies.

Alkaline elution analysis of DNA fragmentation induced during apoptosis

We report that alkaline elution analysis fails to provide a complete profile of DNA fragmentation induced by some genotoxic agents, particularly if these agents induce apoptotic cell death resulting in fragmentation of DNA into oligonucleosomal length multimers. It was questioned whether these oligonucleosome fragments are responsible for the more rapidly eluting component of DNA that is observed as a biphasic elution profile when cells treated with certain genotoxic agents are subjected to alkaline elution. The results of this study indicate that DNA fragmented during apoptotic cell death is eluted in fractions before alkaline denaturation that are normally discarded. Collection of fractions prior to alkaline denaturation is recommended for complete evaluation of the total spectrum of damage induced by genotoxic agents, especially when the compound is suspected of inducing cell death by apoptosis.